TY - JOUR
T1 - Complexes of a functionally modified pyrazole derived ligand - Mononuclear zinc(II), dinuclear nickel(II) and a rare pentanuclear cadmium(II) complex with a TBP core and their photoluminescence studies
AU - Konar, Saugata
AU - Jana, Atanu
AU - Das, Kinsuk
AU - Ray, Sangita
AU - Chatterjee, Sudipta
AU - Kar, Susanta Kumar
PY - 2012/10/26
Y1 - 2012/10/26
N2 - The pyrazole based ditopic ligand PzCAP (HL, 5-methyl-N′-(1- (pyridine-2-yl)ethylidene)-1H-pyrazole-3 carbohydrazide) reacts with Ni(ClO 4)2·6H2O, Zn(ClO4) 2·6H2O and Cd(ClO4)2· 6H2O to form a new alkoxide bridged binuclear Ni(II) complex [Ni 2(PzCAP)3](ClO4)3·6(H 2O) (1), a mononuclear Zn(II) complex [Zn(PzCAP)2] (ClO4)(H2O) (2) and a self assembled pentanuclear Cd(II) complex [Cd5(PzCAP)6](ClO4)4(H 2O) (3). These complexes have been characterized crystallographically and spectroscopically. In complex 1, the three ligand molecules display variable denticity towards the Ni(II) centers, one ligand behaves as tetradentate and two others behave as tridentate ligands to create distorted octahedral environments around the two Ni(II) centers, with N5O and N4O2 chromophores. In 2, the same ligand, using keto and enolic oxygen atoms, produces a distorted octahedral environment around the Zn(II) center with a N4O2 chromophore. Complex 3 has a pentanuclear core with a trigonal bipyramidal arrangement of Cd(II) atoms, where the axial metal centers (Cd2 and Cd4) have N3O3 chromophores and the equatorial centers (Cd1, Cd3 and Cd5) have N 4O2 chromophores, with distorted octahedral arrangements around the metal centers. Interestingly, the pyrazole unit remains inactive to coordination for complex 2, whereas this unit takes part in coordination for 1 and 3. The ligand HL, complex 2 and complex 3 show fluorescence, while in 1 the fluorescence is substantially quenched compared to the ligand (HL) and its Zn and Cd complexes. As the ligand is capable of using different binding modes, according to the demands of the complex, the emission properties also change accordingly.
AB - The pyrazole based ditopic ligand PzCAP (HL, 5-methyl-N′-(1- (pyridine-2-yl)ethylidene)-1H-pyrazole-3 carbohydrazide) reacts with Ni(ClO 4)2·6H2O, Zn(ClO4) 2·6H2O and Cd(ClO4)2· 6H2O to form a new alkoxide bridged binuclear Ni(II) complex [Ni 2(PzCAP)3](ClO4)3·6(H 2O) (1), a mononuclear Zn(II) complex [Zn(PzCAP)2] (ClO4)(H2O) (2) and a self assembled pentanuclear Cd(II) complex [Cd5(PzCAP)6](ClO4)4(H 2O) (3). These complexes have been characterized crystallographically and spectroscopically. In complex 1, the three ligand molecules display variable denticity towards the Ni(II) centers, one ligand behaves as tetradentate and two others behave as tridentate ligands to create distorted octahedral environments around the two Ni(II) centers, with N5O and N4O2 chromophores. In 2, the same ligand, using keto and enolic oxygen atoms, produces a distorted octahedral environment around the Zn(II) center with a N4O2 chromophore. Complex 3 has a pentanuclear core with a trigonal bipyramidal arrangement of Cd(II) atoms, where the axial metal centers (Cd2 and Cd4) have N3O3 chromophores and the equatorial centers (Cd1, Cd3 and Cd5) have N 4O2 chromophores, with distorted octahedral arrangements around the metal centers. Interestingly, the pyrazole unit remains inactive to coordination for complex 2, whereas this unit takes part in coordination for 1 and 3. The ligand HL, complex 2 and complex 3 show fluorescence, while in 1 the fluorescence is substantially quenched compared to the ligand (HL) and its Zn and Cd complexes. As the ligand is capable of using different binding modes, according to the demands of the complex, the emission properties also change accordingly.
KW - Cadmium
KW - Crystal structure
KW - Nickel
KW - Photoluminescence
KW - Pyrazole derived ditopic ligand
KW - Zinc
UR - http://www.scopus.com/inward/record.url?scp=84866494188&partnerID=8YFLogxK
U2 - 10.1016/j.poly.2012.07.080
DO - 10.1016/j.poly.2012.07.080
M3 - Article
AN - SCOPUS:84866494188
SN - 0277-5387
VL - 47
SP - 143
EP - 150
JO - Polyhedron
JF - Polyhedron
IS - 1
ER -