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Designing a heterotrinuclear Cu II —Ni II —Cu II complex from a mononuclear Cu II Schiff base precursor with dicyanamide as a coligand: synthesis, crystal structure, thermal and photoluminescence properties
Author(s) -
Hopa Cigdem,
Cokay Ismail
Publication year - 2016
Publication title -
acta crystallographica section c
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.304
H-Index - 17
ISSN - 2053-2296
DOI - 10.1107/s205322961600944x
Subject(s) - dicyanamide , chemistry , schiff base , nickel , crystallography , thermal decomposition , crystal structure , ligand (biochemistry) , copper , medicinal chemistry , stereochemistry , organic chemistry , biochemistry , ionic liquid , receptor , catalysis
Schiff bases are considered `versatile ligands' in coordination chemistry. The design of polynuclear complexes has become of interest due to their facile preparations and varied synthetic, structural and magnetic properties. The reaction of the `ligand complex' [Cu L ] {H 2 L is 2,2′‐[propane‐1,3‐diylbis(nitrilomethanylylidene)]diphenol} with Ni(OAc) 2 ·4H 2 O (OAc is acetate) in the presence of dicyanamide (dca) leads to the formation of bis(dicyanamido‐1κ N 1 )bis(dimethyl sulfoxide)‐2κ O ,3κ O ‐bis{μ‐2,2′‐[propane‐1,3‐diylbis(nitrilomethanylylidene)]diphenolato}‐1:2κ 6 O , O ′: O , N , N ′, O ′;1:3κ 6 O , O ′: O , N , N ′, O ′‐dicopper(II)nickel(II), [Cu 2 Ni(C 17 H 16 N 2 O 2 ) 2 (C 2 N 3 ) 2 (C 2 H 6 OS) 2 ]. The complex shows strong absorption bands in the frequency region 2155–2269 cm −1 , which clearly proves the presence of terminal bonding dca groups. A single‐crystal X‐ray study revealed that two [Cu L ] units coordinate to an Ni II atom through the phenolate O atoms, with double phenolate bridges between Cu II and Ni II atoms. Two terminal dca groups complete the distorted octahedral geometry around the central Ni II atom. According to differential thermal analysis–thermogravimetric analysis (DTA–TGA), the title complex is stable up to 423 K and thermal decomposition starts with the release of two coordinated dimethyl sulfoxide molecules. Free H 2 L exhibits photoluminescence properties originating from intraligand (π–π*) transitions and fluorescence quenching is observed on complexation of H 2 L with Cu II .