Research Article Synthesis, Crystal Structure, and Antimicrobial...

Research ArticleSynthesis Crystal Structure and AntimicrobialProperties of a Novel 1-D Cobalt Coordination Polymer withDicyanamide and 2-Aminopyridine

Amah Colette Benedicta Yuoh1 Moise Ondoh Agwara1 Divine Mbom Yufanyi2

Mariam Aseng Conde3 Rajamony Jagan4 and Kenneth Oben Eyong5

1Department of Inorganic Chemistry Faculty of Science University of Yaounde I PO Box 812 Yaounde Cameroon2Department of Chemistry Faculty of Science The University of Bamenda PO Box 39 Bambili Bamenda Cameroon3Departement de Chimie Faculte des Sciences Universite de Douala Douala Cameroon4Sophisticated Analytical Instruments Facility Indian Institute of Technology Madras Chennai 600036 India5Department of Organic Chemistry Faculty of Science University of Yaounde I PO Box 812 Yaounde Cameroon

Correspondence should be addressed to Moise Ondoh Agwara agwara29yahoocom

Received 6 April 2015 Revised 4 June 2015 Accepted 7 June 2015

Academic Editor Alfonso Castineiras

Copyright copy 2015 Amah Colette Benedicta Yuoh et al This is an open access article distributed under the Creative CommonsAttribution License which permits unrestricted use distribution and reproduction in any medium provided the original work isproperly cited

A novel one-dimensional coordination polymer bis(2-aminopyridine)-120583-bis(dicyanamido) cobaltate(II) has been synthesized andcharacterized by elemental analyses and infrared and ultraviolet visible spectroscopies and the structure has been determined bysingle crystal X-ray diffraction Co(II) ion in the complex is coordinated to two axial 2-aminopyridine ligands through the pyridineN-atom and four equatorial dicyanamide ligands to give a CoN

6slightly distorted octahedral coordination environment around the

metal ion The amino N-atom forms intrachain hydrogen bonds Antimicrobial screening of the complex against eight pathogenicmicroorganisms (four bacteria and four fungi) isolated from humans indicates that the complex is moderately active

1 Introduction

Transition metal complexes of N-donor heterocyclic ligandsare of interest due to their applications in biology pharmacol-ogy magnetism and so forth [1] Pyridine and its deriva-tives are known for their use in the design and synthesisof multifunctional compounds as well as their biologicaland pharmacological applications as anticoagulants antihis-tamines antiseptics antiarrhythmics and antirheumatics [2ndash4] Amongst the pyridine derivatives 2-aminopyridine (2-ampy) a potential bidentate ligand with two nitrogen donoratoms is of great pharmacological importance because itis used in the synthesis of pharmaceuticals such as anti-histamines and anti-inflammatories [5] 2-ampy has alsobeen shown to have a major influence on the formationof transition metal molybdates in which it acts as a bufferand forms weaker complexes with the transition metals thuspreventing their hydrolysis [6] A survey of the reported

crystal structures of 2-ampy with different metal ions indi-cates that 2-ampy exhibits different bonding modes it mostlyacts as a monodentate ligand through its pyridine nitrogenatom [4 7ndash11] though coordination through the exocyclicaminoN-atom (a less commonmode) has also been reported[12 13] When it coordinates through the pyridine N-atomthe formation of additional H-bonds through the exocyclicamine N-atom is possible [14] It also forms chelates witha bidentate coordination mode through the pyridine Nand exocyclic amine N atoms [15] Several mixed ligandcomplexes containing 2-ampy have also been synthesizedwith different properties and diverse applications [7 9ndash12 16ndash25]

Dicyanamide (dca) has been used extensively as a build-ing block in supramolecular chemistry and crystal engineer-ing [26] This pseudohalide shows versatility in its coordi-nation modes it can act as a monodentate ligand through

Hindawi Publishing CorporationInternational Journal of Inorganic ChemistryVolume 2015 Article ID 106838 8 pageshttpdxdoiorg1011552015106838

2 International Journal of Inorganic Chemistry

nitrile nitrogen as a bidentate ligand through terminal nitrilenitrogen atoms or as a bridging ligand in varied bridgingmodes [26ndash31] The versatile coordination ability of dca hasled to the design and synthesis of several metal-dicyanamidecomplexes with varied topologies and magnetic properties[26 27]

The chemistry of cobalt(II) complexes with O- and N-donor ligands has been extensively studied and it was foundto have diverse properties [1 7 20 30 32] Some of the com-plexes have been shown to possess antitumor properties [33]as well as antimicrobial activity against resistant microbialstrains [12 34 35]

The increased resistance of microorganisms to antimi-crobial agents imposes the search for alternative and morepotent agents The improved biological activity of severaltransition metal complexes upon coordination to differentN-containing heterocyclic ligands reported has caused thedesign and synthesis of these complexes [33 36]

In view of the varied applications of cobalt mixed ligandcomplexes and exploring the good biological properties ofcobalt and 2-ampy as well as the structure-directing proper-ties of dca we report herein the crystal structure of a novelcobalt(II) coordination polymer containing 2-ampy and dcaThe biological activity of the complex towards some resistantpathogens evaluated using in vitro assays is also presented

2 Experimental

21 Materials and Method All chemicals and solvents wereobtained from commercial sources and used as received

22 Synthesis of the Complex 10mL ethanolwater (1 1) solu-tion of sodium dicyanamide and NaC

2N3(036 g 4mmol)

were added dropwise to a stirred ethanolic solution (10mL)of cobalt nitrate hexahydrate and Co(NO

3)2sdot6H2O (059 g

2mmol) at room temperatureThe resulting pinkmixturewasstirred for 30min after which an ethanolic solution (10mL) of2-aminopyridine (077 g 8mmol) was added dropwise Theresultingmixture was further stirred for 1 h after which a pinkprecipitate was afforded The precipitate was filtered washedwith distilled water air-dried and weighed (yield 53) Thefiltrate was allowed to evaporate at room temperature andpink crystalswere obtained [Co(2-ampy)

2(dca)2] yield 53

Pink mp 246∘C Element Anal Calc for CoC14H14N10 C

4410 H 370 N 3674 Found C 4400 H 368 N 3684FTIR (cmminus1) 3478 (]N-H) 2241 and 1489 (]CequivN) 1329 (]CN)and 434 and 560 (]M-N)

23 Characterization Techniques The melting point temper-ature was recorded using the Leica VMHB Kofler systemConductivity measurement was carried out in distilled waterusing a CD810 Tacussel Electronic Conductometer at roomtemperature Elemental analysis (C H N) was carried outon a Flash 2000 Thermo Scientific analyzer The infraredspectrum was recorded using a Bruker ALPHA-P spec-trophotometer directly on a small sample of the complexin the range 400ndash4000 cmminus1 while the UV-visible spectrum

of an ethanolic solution of the complex was recorded usinga Bruker HACH DR 3900 UV-Visible spectrophotometer atroom temperature

24 Single Crystal X-Ray Structure Determination Inten-sity data for the compound was collected using a BrukerAXS Kappa APEX II single crystal CCD Diffractometerequipped with graphite-monochromated MoK120572 radiation(120582 = 071073 A) at room temperature The selected crystalfor the diffraction experiment had a dimension of 025 times025 times 02mm3 Accurate unit cell parameters were deter-mined from the reflections of 36 frames measured in threedifferent crystallographic zones by the method of differencevectors The data collection data reduction and absorp-tion correction were performed by APEX2 SAINT-Plusand SADABS programs [37] The structure was solved bydirect methods procedure using SHELXS-97 program [38]and the nonhydrogen atoms were subjected to anisotropicrefinement by full-matrix least squares on 1198652 using SHELXL-97 program [38] The positions of all the hydrogen atomswere identified from difference electron density map andwere fixed accordingly All the aromatic hydrogen atomswereconstrained to ride on the corresponding nonhydrogen atomswith a distance of C-H = 093 A and Uiso(H) = 12Ueq(C)whereas the hydrogen atoms associated with all the N atomswere restrained to a distance of N-H = 088(2) A

25 Antimicrobial Tests The antimicrobial tests were carriedout in the laboratory of Phytobiochemical and MedicinalPlant Study University of Yaounde I The tests were done oneight pathogenic microorganisms 4 yeasts Candida albicansATCC P37039 Candida albicans 194B Candida glabrata44B and Cryptococcus neoformans and 4 bacterial strainsGram-positive Staphylococcus aureus CIP 7625 and Gram-negatives Pseudomonas aeruginosa CIP 76110 Salmonellatyphi and Escherichia coliATCC 25922 obtained fromCentrePasteur Yaounde Cameroon Reference antibacterial drugchloramphenicol and antifungal drug nystatinwere evaluatedfor their antibacterial and antifungal activities and theirresults were compared with those of the free ligands and thecomplex

The disk diffusion method using Muller Hinton Agarfrom the protocol described by the National Committee forClinical Laboratory Standard (NCCLS 2004) was used forpreliminary screening

Mueller-Hinton agar was prepared from a commerciallyavailable dehydrated base according to the manufacturerrsquosinstructions Several colonies of each microorganism werecollected and suspended in saline (09 NaCl) Then theturbidity of the test suspension was standardized to matchthat of a 05 McFarland standard (corresponds to approx-imately 15 times 108 CFUmL for bacteria or 1 times 106 to 5 times106 cellsmL for yeast) Each compound or reference wasaccurately weighed and dissolved in the appropriate diluents(DMSO at 10 methanol at 10 or distilled water) toyield the required concentration (2mgmL for compound or1mgmL for reference drug) using sterile glassware

International Journal of Inorganic Chemistry 3

Whatman filter paper number 1 was used to prepare disksapproximately 6mm in diameter which were packed up withaluminum paper and sterilized by autoclaving Then 25120583Lof stock solutions of compound or positive control weredelivered to each disk leading to 50120583g of compound or 25 120583gof reference drug

The dried surface of a Muller-Hinton agar plate wasinoculated by flooding over the entire sterile agar surfacewith 500120583L of inoculum suspensions The lid was left ajarfor 3 to 5 minutes to allow for any excess surface moistureto be absorbed before applying the drug impregnated disksDisks containing the compounds or antimicrobial agentswere applied within 15 minutes of inoculating the MHAplate Six disks per petri dish were plated The plates wereinverted and placed in an incubator set to 35∘C After 18hours (for bacteria) and 24 hours (for yeasts) of incubationeach plate was examined The diameters of the zones ofcomplete inhibition (as judged by the unaided eye) weremeasured including the diameter of the disk Zones weremeasured to the nearest whole millimeter using slidingcalipers which were held on the back of the inverted petriplate All experiments were carried out in duplicate Thecompound was considered active against a microbe if theinhibition zone was 6mm and above

3 Results and Discussion

31 Synthesis of the Complex The title complex is pink andair stable with a sharp melting point (246∘C) indicatingits purity The molar conductivity value of the complex is675Ωcmminus2molminus1 in water indicating that it is a nonelec-trolyte

32 X-Ray Crystal Structure The ORTEP view of the crys-tal structure of bis(2-aminopyridine)-120583-bis(dicyanamido)cobaltate(II) [Co(2-ampy)

2(dca)2] together with the atom

numbering scheme used in the corresponding tables isshown in Figure 1 The crystal packing diagram for [Co(2-ampy)

2(dca)2] seen along the crystallographic 119886-axes is

shown in Figure 2 and the 1-D polymeric chain structure ofthe complex is shown in Figure 3The crystal data is presentedin Table 1 while the selected bond lengths and bond anglesare shown in Table 2

The complex crystallizes in themonoclinic crystal systemwith space group P2

1c The asymmetric unit consists of one

2-ampy molecule one dicyanamide anion and one Co(II)ion The crystal structure shows that Co1 adopts a slightlydistorted octahedral environment (CoN

6) in which it is cova-

lently bonded to two pyridine N-atoms (Co-N1 2193(3) A)arranged axially and four nitrile N-atoms (Co1-N3 2126(2) Aand Co1-N5 2128(2) A) from four dca anions in equatorialpositionsThe Co1-N1 bond length is slightly longer than thatreported for other cobalt complexes wih 2-ampy [4 7 9 20]The Co1-N3 (2126 A) and Co1-N5 (2128 A) bond lengths aresimilar to values reported in the literature for other Co-Nbondswith nitrileN [26 30]Thedca ligand adopts a bridgingcoordination mode through the terminal nitrile N-atoms Inthe equatorial plane the bonding configuration of dca around

Table 1 Crystal data and structure refinement for [Co(2-ampy)2(dca)2]

Empirical formula C14H14CoN10

Formula weight 38128Temperature 293(2) KWavelength 071073 ACrystal system MonoclinicSpace group P21c

Unit cell dimensions

119886 = 74488(4) A119887 = 148145(8) A119888 = 73934(4) A120572 = 90∘

120573 = 102016(3)∘

120574 = 90∘

Volume 79799(7) A3

119885 2Density (calculated) 1587mgm3

Absorption coefficient 1097mmminus1

119865(000) 390Crystal size 025 times 025 times 020mmTheta range for data collection 275 to 2747∘

Limiting indices minus9 le ℎ le 9 minus19 le 119896 le 19 minus9 le 119897 le 9Reflections collectedunique 146701813 [119877(int) = 00543]Completeness to theta 2747 990Absorption correction Semiempirical from equivalentsMax and min transmission 08105 and 07711Refinement method Full-matrix least-squares on 1198652

Datarestraintsparameters 181344145Goodness-of-fit on 1198652 1102Final 119877 indices [119868 gt 2 sigma(119868)] 1198771 = 00432 1199081198772 = 01142119877 indices (all data) 1198771 = 00568 1199081198772 = 01258

the Co1 atoms is nonlinear as evidenced by the bond anglesC6-N3-Co1 (1649∘) andC7-N5-Co1 (1577∘)This observationis consistent with the literature reports [30] Each Co1 atomis linked to two Co1 atoms through two 15-120583

2-dca bridges

resulting in a 1-D polymeric chain structure (Figure 3)Thereare no intermolecular hydrogen bonds in the complex butonly intrachain H-bonds between the exocyclic amino groupand dca nitrogen atom (N2-Hsdot sdot sdotN3) and that between N-atoms of dca (N5sdot sdot sdotN3) as well as short contacts The chainsare held together by these short contacts

33 IR Spectroscopy The relevant IR bands are summarizedin Table 3 In the spectrum of 2-ampy the absorption bandsat 3478 and 3287 cmminus1 in the ligand assigned to ]as(N-H) and]s(N-H) respectively are not shifted in the complex indicatingthat the amino N-atom is not participating in bonding[4] This observation is consistent with the X-ray crystalstructure that shows coordination of the 2-ampy ligand onlythrough the pyridine N-atom The sharp vibration band at1557 cmminus1 attributed to ]C=N of 2-ampy has been shiftedto 1549 cmminus1 in the complex indicating its participation inbonding [7] The spectra of the dca ligand and the complex


N1

N2

N5

C1

C5

C7

C4

C3C2

C3ii

C2ii

C4ii

C5ii

C1ii

N1ii

N2ii

N3iii

C6iiiN4iii

N5i C7i

C7ii N5ii

N4 C6N3

Col

N3iiC6ii N4ii

C7v N5v

N4iv

N3iv

C6iv

Figure 1 ORTEP view of the complex [Co(2-ampy)2(dca)2] together with the numbering scheme

show strong absorption bands in the 2310ndash2100 cmminus1 regionattributed to the ]s + ]as (CequivN) ]as (CequivN) and ]s (CequivN)vibrational modes of dca [27 30]The appearance of two newcharacteristic bands 434 cmminus1 and 560 cmminus1 in the spectrumof the complex which were not found in the spectra of theligands indicates the presence of M-N bonding between themetal and the nitrogen atoms of both 2-aminopyridine anddca This observation is confirmed by the X-ray structure ofthe complex which shows that cobalt is bonded to both 2-ampy and dca through N-atoms

34 UV-Visible Spectroscopy In octahedral symmetry six-coordinate high-spin cobalt(II) exhibits three spin-allowedelectronic transitions assigned as 4T1g(F) rarr

4T2g4T1g(F)

rarr4A2g and

4T1g(F) rarr4T1g(P) [27] The UV-vis spectrum

of the title compound reveals two (d-d) absorption bands at498 nm and 642 nm which correspond to 4T1g(F) rarr

4T2gand 4T1g(F) rarr

4T1g(P) transitions respectively [27] Thisdiscloses octahedral geometryThe band at 427 nm ismaskedby the broad band at 498 nm This observation is consistentwith octahedral geometry around the Co(II) center andthis is confirmed by the X-ray structure of the complexIn octahedral symmetry six-coordinate high-spin cobalt(II)exhibits three spin-allowed electronic transitions assigned as4T1g(F) rarr

4T2g4T1g(F) rarr

4A2g and4T1g(F) rarr

4T1g(P)[27]

35 Antimicrobial Tests The potency of the metal salt 2-aminopyridine dca and the complex together with the ref-erence antibacterial drug (chloramphenicol) and antifungal


a

c

b

Figure 2 Packing diagram of the complex showing hydrogen bonding scheme

Figure 3 1-D polymeric chain structure of the complex

drug (nystatin) was evaluated against four bacteria andfour fungi strains The results of the preliminary screeningobtained are presented in Table 4

The results indicate that dca exhibits the highest activityagainst the pathogens especially against the fungi species fol-lowed by the metal salt with a generally high activity against

the pathogensThe ligand 2-aminopyridine shows a relativelylow activity against both fungi and bacteria speciesThemetalcomplex shows moderate activity compared to that of thefree ligands The complex is most active against the fungiC albicans 194B C glabrata 44B and the bacteria species Paeruginosa and S typhi The activity of the complex towards


Table 2 Selected bond lengths [A] and angles [∘] for [Co(2-ampy)2(dca)2]

Co(1)-N(3) 2126(2) N(3)-Co(1)-N(3)1 1800Co(1)-N(3)1 2126(2) N(3)-Co(1)-N(5) 9228(10)Co(1)-N(5) 2128(2) N(3)1-Co(1)-N(5) 8772(10)Co(1)-N(5)1 2128(2) N(3)-Co(1)-N(5)1 8772(10)Co(1)-N(1)1 2193(3) N(3)1-Co(1)-N(5)1 9228(10)Co(1)-N(1) 2193(3) N(5)-Co(1)-N(5)1 18000(9)N(1)-C(1) 1342(4) N(3)-Co(1)-N(1)1 9168(10)N(1)-C(5) 1350(4) N(3)1-Co(1)-N(1)1 8832(10)N(5)-C(7) 1134(3) N(5)-Co(1)-N(1)1 9202(10)N(2)-C(1) 1360(4) N(5)1-Co(1)-N(1)1 8798(10)C(5)-C(4) 1364(5) N(3)-Co(1)-N(1) 8832(10)C(3)-C(2) 1358(6) N(3)1-Co(1)-N(1) 9168(10)C(1)-C(2) 1391(5) N(5)-Co(1)-N(1) 8798(10)C(7)-N(4)2 1305(15) N(5)1-Co(1)-N(1) 9202(10)C(7)-N(41015840)2 1313(14) N(1)1-Co(1)-N(1) 18000(13)N(3)-C(6) 1127(6) C(1)-N(1)-C(5) 1168(3)N(3)-C(61015840) 1129(6) C(1)-N(1)-Co(1) 1283(2)N(4)-C(7)3 1305(15) C(5)-N(1)-Co(1) 1149(2)N(4)-C(6) 1324(18) C(7)-N(5)-Co(1) 1577(2)N(41015840)-C(61015840) 1310(14) N(1)-C(5)-C(4) 1241(3)N(41015840)-C(7)3 1314(14) N(1)-C(1)-N(2) 1183(3)C(3)-C(2) 1358(6) N(1)-C(1)-C(2) 1219(3)C(1)-C(2) 1391(5) N(2)-C(1)-C(2) 1198(3)

C(3)-C(2)-C(1) 1199(4)Symmetry transformations used to generate equivalent atoms1 minus119909 minus119910 minus119911 + 2 2 119909 119910 119911 minus 1 3 119909 119910 119911 + 1

Table 3 Relevant IR bands of the ligands and complex

Compounds ](N-H) cmminus1 ](CequivN) cm

minus1 ](C=N) cmminus1 ](C-N) cm

minus1 ](M-N) cmminus1

2-ampy 3287 1557 1140 dca 2226 1338

Co(2-ampy)2(dca)2 3478 2241 1489 1329 434560

Table 4 Diameter of zone of inhibition of the complex ligands and the metal salt

Species Zone of inhibition (mm)Co(NO3)2 dca 2-ampy Co(2-ampy)2(dca)2 Chloramphenicol Nystatin

Fungi

C albicans ATCC P37039 85 115 60 60 75 60C albicans 194B 60 75 70 90 145 70C glabrata 44B 75 140 60 80 60 60C neoformans 80 115 60 70 105 95

Bacteria

E coli 70 90 80 60 120 60P aeruginosa 115 60 60 85 115 60

S typhi 110 60 80 85 100 60S aureus 100 60 60 60 140 105

the microorganisms decreases in the order C albicans 194B gtP aeruginosa = S typhi gt C glabrata 44B gt C neoformansgt E coli It shows greater activity towards the fungi thanthe bacteria species and their activities are comparable tothose of the reference drugs used The complex is also more

active than the reference drug nystatin towards the fungispecies This indicates that reaction of metal ions with theligand plays an important role in enhancing its antimicrobialactivity This increase in activity could be due to the reduc-tion of the polarity of the metal ion by partial sharing of


the positive charge with the ligandrsquos donor atoms so thatthere is electron delocalization within the metal complexThis may increase the hydrophobic and lipophilic characterof the metal complex enabling it to permeate the lipid layerof the organism killing them more effectively [39 40]

4 Conclusion

The synthesis of a novel mixed ligand Co(II) 1-D polymerwith 2-aminopyridine and dca has been reported The equa-torial and terminal bridging dca ligands coordinate in anonlinear manner to the central metal ion while the axial2-ampy ligands coordinate to the Co(II) ion through thepyridine N-atoms The Co(II) ion in the complex adoptsa slightly distorted octahedral environment comprising twopyridine N-atoms from 2-aminopyridine and four nitrileN-atoms from the dicyanamide The amino N-atoms areinvolved in intrachain hydrogen bonds The results of thepreliminary antimicrobial screening against four pathogenicbacteria and four fungi species indicate that the complexis moderately active and could be further screened in vitroagainst a wide range of pathogens

Supporting Information

CCDC 1007918 contains the supplementary crystallographicdata for the complex The data can be obtained free ofcharge from The Cambridge Crystallographic Data Centrevia httpswwwccdccamacukdata requestcif

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgment

MoiseOndohAgwaraDivineMbomYufanyiMariamAsengConde and Kenneth Oben Eyong thank the Government ofCameroon for financial support through the Fonds drsquoAppuisa la Recherche

References

[1] C V Sastri D Eswaramoorthy L Giribabu and B GMaiya ldquoDNA interactions of new mixed-ligand complexes ofcobalt(III) and nickel(II) that incorporate modified phenan-throline ligandsrdquo Journal of Inorganic Biochemistry vol 94 no1-2 pp 138ndash145 2003

[2] B Forood B T Flatt C Chassaing and A K Katritzky ldquo2-Aminopyridine derivatives and combinatorial libraries thereofrdquoUnited States Patent US 6458789 B1 Lion Bioscience AG 2002

[3] L E Kapinos and H Sigel ldquoAcid-base and metal ion bindingproperties of pyridine-type ligands in aqueous solution effect ofortho substituents and interrelation between complex stabilityand ligand basicityrdquo Inorganica Chimica Acta vol 337 pp 131ndash142 2002

[4] C Yenikaya M Poyraz M Sarı F Demirci H Ilkimen andO Buyukgungor ldquoSynthesis characterization and biological

evaluation of a novel Cu(II) complexwith themixed ligands 26-pyridinedicarboxylic acid and 2-aminopyridinerdquo Polyhedronvol 28 no 16 pp 3526ndash3532 2009

[5] M Odabasoglu O Buyukgungor G Turgut A KaradagE Bulak and P Lonnecke ldquoCrystal structure spectral andthermal properties of 2-aminopyridinium adipate monoadipicacid dihydraterdquo Journal of Molecular Structure vol 648 no 1-2pp 133ndash138 2003

[6] K Pavani and A Ramanan ldquoInfluence of 2-aminopyridine onthe formation of molybdates under hydrothermal conditionsrdquoEuropean Journal of Inorganic Chemistry no 15 pp 3080ndash30872005

[7] B Dojer A Pevec P Segedin et al ldquoCobalt(II) coordinationcompounds with acetate and 2-aminopyridine ligands synthe-sis characterization structures and magnetic properties of twopolymorphic formsrdquo Inorganica Chimica Acta vol 363 no 7pp 1343ndash1347 2010

[8] M A S Goher and T C W Mak ldquoPreparation and struc-tural characterization of di-120583-azido-bis[azido(2-aminopyri-dine)aquo]dicopper(II) [Cu(2-ampy)(N

3)2(H2O)]2rdquo Inorgan-

ica Chimica Acta vol 85 no 2 pp 117ndash122 1984[9] B Kozlevcar N Lah D Zlindra I Leban and P Segedin

ldquoCopper(II) benzoates and acetates with 2-aminopyridinerdquoActa Chimica Slovenica vol 48 no 3 pp 363ndash374 2001

[10] L Li and F Yuan ldquoSynthesis and structural characteriza-tion of the heteroleptic nickel 2-aminopyridine complex of(acac)(CH

3COO)Ni(2-NH

2Py)2rdquo Synthesis and Reactivity in

Inorganic Metal-Organic and Nano-Metal Chemistry vol 42no 2 pp 205ndash208 2012

[11] K Sakai N Akiyama andMMizota ldquoBis(2-aminopyridine)(221015840-bipyridine)-platinum(II) dinitrate dihydraterdquoActa Crystallo-graphica Section E Structure Reports Online vol 59 no 7 ppm459ndashm461 2003

[12] M M Mashaly ldquoSynthesis and characterization of some newoxorhenium(V) complexes with annulene derivatives and theirbiological activitiesrdquo Synthesis and Reactivity in Inorganic andMetal-Organic Chemistry vol 34 no 1 pp 115ndash144 2004

[13] S Nieto J Perez L Riera V Riera and D Miguel ldquoMetalcomplexes with two different hydrogen-bond donor ligands asanion hostsrdquo Chemical Communications no 22 pp 3279ndash32812009

[14] N Lah P Segedin and I Leban ldquoCrystal structures of twomonomeric copper(II) carboxylates with 2-aminopyridinerdquoStructural Chemistry vol 13 no 3-4 pp 357ndash360 2002

[15] N Kanematsu M Ebihara and T Kawamura ldquoPreparationstructure and electrochemical behavior of dinuclear cycloocta-diene-chelated Ir(I) complexes with 2-aminopyridinato bridg-esrdquo Inorganica Chimica Acta vol 292 no 2 pp 244ndash248 1999

[16] S A Al-Jibori Q K A Al-Jibori H Schmidt K Merzweiler CWagner and G Hogarth ldquoPalladium(II) saccharinate (sac) andthiosaccharinate (tsac) complexes with 2-aminopyridine (2-ampy) 2-acetylaminopyridine (2-aampy) and 2-acetylamino-pyrimidine (2-aampym) co-ligands X-ray crystal structures oftrans-[Pd(sac)

2(ampy)

2] and solvatomorphs trans-[Pd(sac)

2(2-

aampy)2]sdotS (S =CHCl

3 thf)rdquo Inorganica Chimica Acta vol 402

pp 69ndash74 2013[17] P L Andreu J A Cabeza V Riera Y Jeannin and D

Miguel ldquoThe different reactivity of 2-aminopyridines and 2-pyridone with [Ru

3(CO)12] X-ray crystal structure of [Ru

3(120583-

H)(1205833-anpy)(CO)

9] (hanpy = 2-anilinopyridine)rdquo Journal of the

Chemical Society Dalton Transactions no 7 pp 2201ndash22061990


[18] S Caglar I E Aydemir E Adiguzel B Caglar S Demir andO Buyukgungor ldquoFour copper(II) diclofenac complexes withpyridine derivatives synthesis crystal structures spectroscopicproperties thermal analysis and catechol oxidase activitiesrdquoInorganica Chimica Acta vol 408 pp 131ndash138 2013

[19] E Clot J Chen D-H Lee et al ldquoDouble geminal C-Hactivation and reversible 120572-elimination in 2-aminopyridineiridium(III) complexes the role of hydrides and solvent inflattening the free energy surfacerdquo Journal of the AmericanChemical Society vol 126 no 28 pp 8795ndash8804 2004

[20] B Dojer A Pevec M Jagodic M Kristl and M Dro-fenik ldquoThree new cobalt(II) carboxylates with 2- 3- and 4-aminopyridine syntheses structures and magnetic propertiesrdquoInorganica Chimica Acta vol 383 pp 98ndash104 2012

[21] A Moghimi S MMoosavi D Kordestani et al ldquoPyridine-26-bis(monothiocarboxylic) acid and 2-aminopyridine as buildingblocks of a novel proton transfer compound solution and X-raycrystal structural studiesrdquo Journal of Molecular Structure vol828 no 1ndash3 pp 38ndash45 2007

[22] J H K Yip Suwarno and J J Vittal ldquoSyntheses and elec-tronic spectroscopy of [PtL(L1015840)][ClO

4] complexes (HL = 6-

phenyl-221015840-bipyridine L1015840 = pyridine 4-aminopyridine 2-aminopyridine and 26-diaminopyridine)rdquo Inorganic Chem-istry vol 39 no 16 pp 3537ndash3543 2000

[23] F A Mautner A Egger B Sodin et al ldquoTwo new azidobridging Mn(II) 1D systems synthesis and characterization oftrans-[Mn(N

3)2(2-aminopyridine)

2]119899and trans-[Mn(N

3)2(4-

azidopyridine)2]119899rdquo Journal of Molecular Structure vol 969 no

1ndash3 pp 192ndash196 2010[24] L Mei L S Tai J Li F H Tao L X Liang and Y S Zhong

ldquoSynthesis and catalytic activity of DI-120583-methoxo-bis[(2-aminopyridine) (chloro)copper(II)] and m-xylylenediamineZn(OAc)

2rdquo Russian Journal of Coordination Chemistry vol 37

no 2 pp 153ndash159 2011[25] G Sharma and A K Narula ldquoSynthesis and optoelectronic

properties of three Eu(III)-dipicolinate complexes based on120572-picolinic acid 2-aminopyridine and 2-hydroxypyridine assecondary ligandsrdquo Journal of Materials Science Materials inElectronics vol 26 no 2 pp 1009ndash1017 2015

[26] H-L Sun Z-M Wang and S Gao ldquoSynthesis crystal struc-tures and magnetism of cobalt coordination polymers basedon dicyanamide and pyrazine-dioxide derivativesrdquo InorganicChemistry vol 44 no 7 pp 2169ndash2176 2005

[27] A Mohamadou G A van Albada H Kooijman B WieczorekA L Spek and J Reedijk ldquoThe binding mode of the ambiden-tate ligand dicyanamide to transitionmetal ions can be tuned bybisimidazoline ligands with H-bonding donor property at therear side of the ligandrdquo New Journal of Chemistry vol 27 no 6pp 983ndash988 2003

[28] K S Murray S R Batten B Moubaraki D J Price andR Robson ldquoMolecular magnetism in manganese dicyanamideextended network structuresrdquo Molecular Crystals and LiquidCrystals Science and Technology Section A Molecular Crystalsand Liquid Crystals vol 335 no 1 pp 313ndash322 1999

[29] W-Z Shen X-Y Chen P Cheng D-Z Liao S-P Yan andZ-H Jiang ldquoCobalt(II) complexes with dicyanamidemdashfrombinuclear entities to chainsrdquo Zeitschrift fur Anorganische undAllgemeine Chemie vol 629 no 14 pp 2591ndash2595 2003

[30] L Zheng ldquoSynthesis crystal structures and magnetic prop-erties of ternary M(II)-dicyanamide-hydroxypyridine com-plexesrdquo Journal of Inorganic Chemistry vol 2013 Article ID206589 10 pages 2013

[31] Z-W Li P-P Yang X-L Wang and L-C Li ldquoSynthesesstructures and magnetic properties of two 1-D dicyanamidemanganese(III) complexes with Schiff-base ligandsrdquo Journal ofCoordination Chemistry vol 63 no 9 pp 1538ndash1545 2010

[32] J Luo L Qiu B Liu X Zhang F Yang and L CuildquoSynthesis structure and magnetic properties of two cobalt(II)dicyanamide (dca) complexes with heterocyclic nitrogendonors tetra(2-pyridyl)pyrazine (tppz) and 246-Tri(2-pyridyl)-135-triazine (tptz) [Co

2(tppz)(dca)

4]sdotCH3CN and

[Co(tptz)(dca)(H2O)](dca)rdquo Chinese Journal of Chemistry vol

30 no 3 pp 522ndash528 2012[33] H Gopinathan N Komathi and M N Arumugham ldquoSynthe-

sis structure DNA binding cleavage and biological activity ofcobalt (III) complexes derived from triethylenetetramine and110 phenanthroline ligandsrdquo Inorganica Chimica Acta vol 416pp 93ndash101 2014

[34] M O Agwara P T Ndifon N B Ndosiri A G PaboudamDM Yufanyi andAMohamadou ldquoSynthesis characterisationand antimicrobial activities of cobalt(II) copper(II) and zinc(II)mixed-ligand complexes containing 110-phenanthroline and221015840-bipyridinerdquo Bulletin of the Chemical Society of Ethiopia vol24 no 3 pp 383ndash389 2010

[35] M M Mashaly Z H Abd-Elwahab and A A Faheim ldquoPrepa-ration spectral characterization and antimicrobial activities ofSchiff base complexes derived from 4-aminoantipyrine Mixedligand complexes with 2-aminopyridine 8-hydroxyquinolineand oxalic acid and their pyrolytical productsrdquo Journal of theChinese Chemical Society vol 51 no 5 pp 901ndash915 2004

[36] S Saha A Sasmal C R Choudhury et al ldquoSynthesis crystalstructure antimicrobial screening and density functional the-ory calculation of nickel(II) cobalt(II) and zinc(II) mononu-clear Schiff base complexesrdquo Inorganica Chimica Acta vol 425pp 211ndash220 2015

[37] Bruker APEX2 SAINT-Plus and XPREP Bruker AXS Madi-son Wis USA 2004

[38] G M Sheldrick ldquoA short history of SHELXrdquo Acta Crystallo-graphica Section A vol 64 no 1 pp 112ndash122 2008

[39] A Colette AMOndoh DM Yufanyi andD S YanickGaelleldquoSynthesis crystal structure and antimicrobial properties of ananhydrous copper(II) complex of pyridine-2-carboxylic acidrdquoInternational Journal of Chemistry vol 7 no 1 pp 10ndash20 2015

[40] E N Nfor P F Asobo J Nenwa et al ldquoNickel (II) and iron (II)complexes with azole derivatives synthesis crystal structuresand antifungal activitiesrdquo International Journal of InorganicChemistry vol 2013 Article ID 987574 6 pages 2013

Submit your manuscripts athttpwwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Inorganic ChemistryInternational Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

International Journal ofPhotoenergy


Carbohydrate Chemistry

International Journal of


Journal of

Chemistry


Advances in

Physical Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom

Analytical Methods in Chemistry

Journal of

Volume 2014

Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

SpectroscopyInternational Journal of


The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Medicinal ChemistryInternational Journal of


Chromatography Research International


Applied ChemistryJournal of



Theoretical ChemistryJournal of


Journal of

Spectroscopy

Analytical ChemistryInternational Journal of


Journal of


Quantum Chemistry


Organic Chemistry International

ElectrochemistryInternational Journal of



CatalystsJournal of


nitrile nitrogen as a bidentate ligand through terminal nitrilenitrogen atoms or as a bridging ligand in varied bridgingmodes [26ndash31] The versatile coordination ability of dca hasled to the design and synthesis of several metal-dicyanamidecomplexes with varied topologies and magnetic properties[26 27]

The chemistry of cobalt(II) complexes with O- and N-donor ligands has been extensively studied and it was foundto have diverse properties [1 7 20 30 32] Some of the com-plexes have been shown to possess antitumor properties [33]as well as antimicrobial activity against resistant microbialstrains [12 34 35]

The increased resistance of microorganisms to antimi-crobial agents imposes the search for alternative and morepotent agents The improved biological activity of severaltransition metal complexes upon coordination to differentN-containing heterocyclic ligands reported has caused thedesign and synthesis of these complexes [33 36]

In view of the varied applications of cobalt mixed ligandcomplexes and exploring the good biological properties ofcobalt and 2-ampy as well as the structure-directing proper-ties of dca we report herein the crystal structure of a novelcobalt(II) coordination polymer containing 2-ampy and dcaThe biological activity of the complex towards some resistantpathogens evaluated using in vitro assays is also presented

2 Experimental

21 Materials and Method All chemicals and solvents wereobtained from commercial sources and used as received

22 Synthesis of the Complex 10mL ethanolwater (1 1) solu-tion of sodium dicyanamide and NaC

2N3(036 g 4mmol)

were added dropwise to a stirred ethanolic solution (10mL)of cobalt nitrate hexahydrate and Co(NO

3)2sdot6H2O (059 g

2mmol) at room temperatureThe resulting pinkmixturewasstirred for 30min after which an ethanolic solution (10mL) of2-aminopyridine (077 g 8mmol) was added dropwise Theresultingmixture was further stirred for 1 h after which a pinkprecipitate was afforded The precipitate was filtered washedwith distilled water air-dried and weighed (yield 53) Thefiltrate was allowed to evaporate at room temperature andpink crystalswere obtained [Co(2-ampy)

2(dca)2] yield 53

Pink mp 246∘C Element Anal Calc for CoC14H14N10 C

4410 H 370 N 3674 Found C 4400 H 368 N 3684FTIR (cmminus1) 3478 (]N-H) 2241 and 1489 (]CequivN) 1329 (]CN)and 434 and 560 (]M-N)

23 Characterization Techniques The melting point temper-ature was recorded using the Leica VMHB Kofler systemConductivity measurement was carried out in distilled waterusing a CD810 Tacussel Electronic Conductometer at roomtemperature Elemental analysis (C H N) was carried outon a Flash 2000 Thermo Scientific analyzer The infraredspectrum was recorded using a Bruker ALPHA-P spec-trophotometer directly on a small sample of the complexin the range 400ndash4000 cmminus1 while the UV-visible spectrum

of an ethanolic solution of the complex was recorded usinga Bruker HACH DR 3900 UV-Visible spectrophotometer atroom temperature

24 Single Crystal X-Ray Structure Determination Inten-sity data for the compound was collected using a BrukerAXS Kappa APEX II single crystal CCD Diffractometerequipped with graphite-monochromated MoK120572 radiation(120582 = 071073 A) at room temperature The selected crystalfor the diffraction experiment had a dimension of 025 times025 times 02mm3 Accurate unit cell parameters were deter-mined from the reflections of 36 frames measured in threedifferent crystallographic zones by the method of differencevectors The data collection data reduction and absorp-tion correction were performed by APEX2 SAINT-Plusand SADABS programs [37] The structure was solved bydirect methods procedure using SHELXS-97 program [38]and the nonhydrogen atoms were subjected to anisotropicrefinement by full-matrix least squares on 1198652 using SHELXL-97 program [38] The positions of all the hydrogen atomswere identified from difference electron density map andwere fixed accordingly All the aromatic hydrogen atomswereconstrained to ride on the corresponding nonhydrogen atomswith a distance of C-H = 093 A and Uiso(H) = 12Ueq(C)whereas the hydrogen atoms associated with all the N atomswere restrained to a distance of N-H = 088(2) A

25 Antimicrobial Tests The antimicrobial tests were carriedout in the laboratory of Phytobiochemical and MedicinalPlant Study University of Yaounde I The tests were done oneight pathogenic microorganisms 4 yeasts Candida albicansATCC P37039 Candida albicans 194B Candida glabrata44B and Cryptococcus neoformans and 4 bacterial strainsGram-positive Staphylococcus aureus CIP 7625 and Gram-negatives Pseudomonas aeruginosa CIP 76110 Salmonellatyphi and Escherichia coliATCC 25922 obtained fromCentrePasteur Yaounde Cameroon Reference antibacterial drugchloramphenicol and antifungal drug nystatinwere evaluatedfor their antibacterial and antifungal activities and theirresults were compared with those of the free ligands and thecomplex

The disk diffusion method using Muller Hinton Agarfrom the protocol described by the National Committee forClinical Laboratory Standard (NCCLS 2004) was used forpreliminary screening

Mueller-Hinton agar was prepared from a commerciallyavailable dehydrated base according to the manufacturerrsquosinstructions Several colonies of each microorganism werecollected and suspended in saline (09 NaCl) Then theturbidity of the test suspension was standardized to matchthat of a 05 McFarland standard (corresponds to approx-imately 15 times 108 CFUmL for bacteria or 1 times 106 to 5 times106 cellsmL for yeast) Each compound or reference wasaccurately weighed and dissolved in the appropriate diluents(DMSO at 10 methanol at 10 or distilled water) toyield the required concentration (2mgmL for compound or1mgmL for reference drug) using sterile glassware




















119886 = 74488(4) A119887 = 148145(8) A119888 = 73934(4) A120572 = 90∘

120573 = 102016(3)∘

120574 = 90∘

Volume 79799(7) A3







2-dca bridges




N1

N2

N5

C1

C5

C7

C4

C3C2

C3ii

C2ii

C4ii

C5ii

C1ii

N1ii

N2ii

N3iii

C6iiiN4iii

N5i C7i

C7ii N5ii

N4 C6N3

Col

N3iiC6ii N4ii

C7v N5v

N4iv

N3iv

C6iv




4T2g4T1g(F)

rarr4A2g and





4T2g4T1g(F) rarr


4T1g(P)[27]



a

c

b














2-ampy 3287 1557 1140 dca 2226 1338

Co(2-ampy)2(dca)2 3478 2241 1489 1329 434560



Fungi


Bacteria


S typhi 110 60 80 85 100 60S aureus 100 60 60 60 140 105





4 Conclusion






Acknowledgment


References














3COO)Ni(2-NH









2(ampy)


2(2-






3(120583-

H)(1205833-anpy)(CO)














3)2(4-














2(tppz)(dca)

4]sdotCH3CN and




















Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of




















119886 = 74488(4) A119887 = 148145(8) A119888 = 73934(4) A120572 = 90∘

120573 = 102016(3)∘

120574 = 90∘

Volume 79799(7) A3







2-dca bridges




N1

N2

N5

C1

C5

C7

C4

C3C2

C3ii

C2ii

C4ii

C5ii

C1ii

N1ii

N2ii

N3iii

C6iiiN4iii

N5i C7i

C7ii N5ii

N4 C6N3

Col

N3iiC6ii N4ii

C7v N5v

N4iv

N3iv

C6iv




4T2g4T1g(F)

rarr4A2g and





4T2g4T1g(F) rarr


4T1g(P)[27]



a

c

b














2-ampy 3287 1557 1140 dca 2226 1338

Co(2-ampy)2(dca)2 3478 2241 1489 1329 434560



Fungi


Bacteria


S typhi 110 60 80 85 100 60S aureus 100 60 60 60 140 105





4 Conclusion






Acknowledgment


References














3COO)Ni(2-NH









2(ampy)


2(2-






3(120583-

H)(1205833-anpy)(CO)














3)2(4-














2(tppz)(dca)

4]sdotCH3CN and




















Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


N1

N2

N5

C1

C5

C7

C4

C3C2

C3ii

C2ii

C4ii

C5ii

C1ii

N1ii

N2ii

N3iii

C6iiiN4iii

N5i C7i

C7ii N5ii

N4 C6N3

Col

N3iiC6ii N4ii

C7v N5v

N4iv

N3iv

C6iv




4T2g4T1g(F)

rarr4A2g and





4T2g4T1g(F) rarr


4T1g(P)[27]



a

c

b














2-ampy 3287 1557 1140 dca 2226 1338

Co(2-ampy)2(dca)2 3478 2241 1489 1329 434560



Fungi


Bacteria


S typhi 110 60 80 85 100 60S aureus 100 60 60 60 140 105





4 Conclusion






Acknowledgment


References














3COO)Ni(2-NH









2(ampy)


2(2-






3(120583-

H)(1205833-anpy)(CO)














3)2(4-














2(tppz)(dca)

4]sdotCH3CN and




















Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


a

c

b














2-ampy 3287 1557 1140 dca 2226 1338

Co(2-ampy)2(dca)2 3478 2241 1489 1329 434560



Fungi


Bacteria


S typhi 110 60 80 85 100 60S aureus 100 60 60 60 140 105





4 Conclusion






Acknowledgment


References














3COO)Ni(2-NH









2(ampy)


2(2-






3(120583-

H)(1205833-anpy)(CO)














3)2(4-














2(tppz)(dca)

4]sdotCH3CN and




















Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of









2-ampy 3287 1557 1140 dca 2226 1338

Co(2-ampy)2(dca)2 3478 2241 1489 1329 434560



Fungi


Bacteria


S typhi 110 60 80 85 100 60S aureus 100 60 60 60 140 105





4 Conclusion






Acknowledgment


References














3COO)Ni(2-NH









2(ampy)


2(2-






3(120583-

H)(1205833-anpy)(CO)














3)2(4-














2(tppz)(dca)

4]sdotCH3CN and




















Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of



4 Conclusion






Acknowledgment


References














3COO)Ni(2-NH









2(ampy)


2(2-






3(120583-

H)(1205833-anpy)(CO)














3)2(4-














2(tppz)(dca)

4]sdotCH3CN and




















Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of












3)2(4-














2(tppz)(dca)

4]sdotCH3CN and




















Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of










Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of

Research Article Synthesis, Crystal Structure, and Antimicrobial...

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