Abstract
Ground and excited-state proton transfer and electrical responsive properties along the proton transfer co-ordinate of four donor–acceptor substituted pyrazole derivatives have been investigated using the density function-based range separated hybrid GGA functional ωB97XD with 6-311G(d) basis. Both intrinsic reaction coordinate (IRC) and distinguished co-ordinate (variation of O–H distance of the enol tautomer) have been chosen as a proton transfer co-ordinate of the titled compounds for comparison. Our study reveals that the various electrical responsive parameters like average polarizability (αav), first hyperpolarizability (βav) and global reactivity descriptors e.g., chemical hardness (η), electrophilicity index (ω) along the proton transfer co-ordinate are in conformity with the respective optimum principles. Maximum value of βav is found in the case of nitro substituted pyrazole derivative. Variation of βav along the proton transfer co-ordinate for all compounds have been correlated with the variation of Δµf0/(S1-S0)3 using two-level approximation and electronic special extent (<R2>) along the proton transfer coordinate.
GRAPHICAL ABSTRACT
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Acknowledgments
R.M and U.M thank UGC-BSR and UGC (ref. no. 188/(CSIR-UGC NET JUNE 2019) for their individual research fellowship. Departmental computational facilities from DST-FIST (Ref. No. SR/FST/CSI-235/2011) and UGC-SAP (Ref. No. F.5- 9/2015/DRS-11 (SAP-11) programmes are gratefully acknowledged.
Disclosure statement
No potential conflict of interest was reported by the author(s).