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Electronic Structure of Bis(4‐dimethylaminophenyl)squaraine
Author(s) -
Divya Velayudhan V.,
Suresh Cherumuttathu H.
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.201803543
Subject(s) - chemistry , solvatochromism , ring (chemistry) , electronic structure , molecule , charge (physics) , crystallography , squaric acid , character (mathematics) , computational chemistry , organic chemistry , physics , geometry , mathematics , quantum mechanics
The structural and electronic features of bis(4‐dimethylaminophenyl)squaraine ( 1 ) has been studied using density functional BLYP/ cc‐pVTZ level of theory. The quinoid character of 1 is correlated to the partial double bond character of C‐NMe 2 (1.379 Å) and C−O (1.236 Å) bonds which leads to accumulation of positive charge on NMe 2 groups and negative charge on carbonyl oxygen. Further, the diagonal C1 C3 (2.086 Å) and C2 C4 (2.116 Å) distances of the squaric ring indicated a 1,3 type C−C orbital interaction. Molecular electrostatic potential (MESP) topographical analysis confirmed the charge separated quadrupolar nature of 1 . The MESP minimum, V min located at the carbonyl oxygen, −62.5 kcal/mol, confirmed its highly electron rich character arising from the quinoid structure. The electronic structure of 1 revealed from MESP confirmed its quadrupolar nature and suggested the location of positive charge on NMe 2 groups. The typically used chemical structure drawing of 1 showing +2 charge on the squaraine ring is inaccurate and misleading. The solvatochromic behaviour of 1 can be attributed to its quadrupolar electronic structure wherein the electron rich carbonyl groups provide room for noncovalent interactions with multiple solvent molecules.