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Synthesis, Photophysical, Thermal and Crystallographic Studies of 3‐Aminocoumarin Based Monobasic κ 3 ‐O,N,O‐ tridentate / κ 2 ‐ N,O‐ bidentate Schiff Base Divalent Complexes
Author(s) -
Verma Sanjay K,
Savani Chirag,
Singh Vinay K.
Publication year - 2019
Publication title -
chemistryselect
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.437
H-Index - 34
ISSN - 2365-6549
DOI - 10.1002/slct.201903988
Subject(s) - denticity , chemistry , schiff base , crystallography , monobasic acid , electron paramagnetic resonance , metal , zinc , crystal structure , stereochemistry , polymer chemistry , organic chemistry , nuclear magnetic resonance , physics
The reaction of 3‐Amino coumarin based Schiff base ligands HL 1 and HL 2 with metal acetates in refluxing ethanol affords access to a new series of neutral mononuclear divalent complexes [M II ‐ κ 3 ‐bis‐ O,N,O ‐tridentate Schiff base‐ HL 1 / HL 2 ] {HL 1 , M II =Co ( 1 ), Ni ( 2 ) or Zn ( 3 ); HL 2 , M II =Co ( 4 ), Ni ( 5 ) or Zn ( 6 )}, [Cu II ‐ κ 2 ‐bis‐ N , O ‐bidentate Schiff base‐HL 1 ] ( 7 ) and [Cu II ‐ κ 2 ‐bis‐ N , O ‐bidentate Schiff base ‐ HL 2 ] ( 8 ). Compounds were characterized by microanalysis, standard spectroscopic ( viz . MALDI‐TOF‐MS, IR, 1 H and 13 C NMR, UV‐visible absorption and emission) and TGA/DTA methods. The unambiguous crystal structure of HL 1 , HL 2 , complexes 2 and 3 was determined crystallographically. The IR, UV‐visible, EPR spectral and magnetic studies clearly suggest the κ 3 ‐O,N,O‐ tridentate‐ coordination mode of HL 1 and HL 2 towards cobalt(II), nickel(II) and zinc(II) metal ions in 1–6 and κ 2 ‐ N,O‐ bidentate‐coordination mode towards copper(II) metal ions in 7 and 8 . Notably, compounds fluoresce a medium to strong emissions in the visible region is observed with concomitant Stokes shifts of ≈ 90 nm. UV‐visible transmittance spectral study reveals the semiconducting nature of HL 1 , HL 2 , complexes 1–8 gave with band gap energy of 1.57‐2.24 electron volts. The molecules of HL 1 , HL 2 , 2 and 3 are stabilized by various intermolecular CH…π, CH…O and π…π contacts that efficiently managed the growth of self‐assembly in three dimensions and form infinite molecular layers in the solid state.