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Zinc Dialkylhydroxybenzoates with Unusual Structures: First Example of a Discrete Three‐Blade Paddle‐Wheel and a Solvent Engulfed Coordination Polymer
Author(s) -
Vishnoi Pratap,
Sharma Sunil K.,
Kaleeswaran D.,
Murugavel Ramaswamy
Publication year - 2016
Publication title -
chemistryselect
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.437
H-Index - 34
ISSN - 2365-6549
DOI - 10.1002/slct.201601853
Subject(s) - chemistry , hydrogen bond , supramolecular chemistry , synthon , crystallography , ligand (biochemistry) , steric effects , stacking , pyrazole , stereochemistry , zinc , molecule , crystal structure , organic chemistry , biochemistry , receptor
Abstract Sterically encumbered 4‐hydroxy‐3,5‐diisopropylbenzoic acid (H 2 diphba), bearing a carboxylic acid, a phenol and two iso‐propyl substituents, has been investigated for the first time as a ligand and supramolecular synthon to isolate eight Zn(II) complexes, [Zn 2 (Hdiphba) 3 (OAc)(L)] (L=DMF( 1 ) or pyz ( 2 )), [Zn(Hdiphba) 2 (2,2′‐bpy)] ( 3 ), [Zn(Hdiphba) 2 (1,10‐phen)] ( 4 ), [Zn(Hdiphba) 2 (pz) 2 ] ( 5 ) and [Zn 2 (Hdiphba) 2 (μ 2 ‐dmpz) 2 (Hdmpz) 2 ] ( 6 ), [Zn(Hdiphba) 2 (4,4′‐bpy)] n ⋅4nCH 3 OH ( 7 .4nCH 3 OH), [Zn 2 (Hdiphba) 4 (4,4′‐azobpy)(H 2 O) 2 ] ( 8⋅ H 2 diphba), which have been structurally characterized. Compounds 1 and 2 are rare examples of symmetrically bridged triple‐blade molecular tricarboxylate paddle‐wheels which self‐assemble into hexameric units. Compounds 3 , 4 and 5 are mononuclear complexes, bearing two exposed phenolic –OH groups self‐assembled into 2‐D arrays via both hydrogen bonding and π‐π stacking interactions. Compound 6 is a rare example of bis‐pyrazolate bridged dinuclear Zn(II) complex with two pyrazole N−H and two phenolic ‐OH groups on the molecular periphery to form hydrogen bonds. The use of 4,4’‐bpy leading to a zig‐zag 1‐D polymer 7 composed of [Zn(Hdiphba) 2 (4,4’‐bpy)] n chains, positioned 10.77 Å apart. The 1‐D channels of 7 are occupied by hydrogen bonded methanol with a rare (CH 3 OH) 4 cluster as the repeating unit. Compound 8 is a discrete bimetallic complex, isolated with a free H 2 diphba ligand. The photoluminescence spectra of 1–8 exhibit ligand centered emission at around 325 nm.