Molecular and Electronic Structure and Properties of the Single Benzene‐Based Fluorophores Containing Guanidine Subunit

Glasovac, Zoran; Margetić, Davor; Antol, Ivana (2025) Molecular and Electronic Structure and Properties of the Single Benzene‐Based Fluorophores Containing Guanidine Subunit. Journal of Computational Chemistry, 46 (4). ISSN 0192-8651

PDF - Published Version - article
Available under License Creative Commons Attribution Non-commercial No Derivatives.
Download (1MB)

Official URL: http://doi.org/10.1002/jcc.70054

Abstract

The Gibbs energies of protonation (ΔGp) and the basic photophysical properties for single-benzene fluorophores (SBFs) containing guanidine and/or amino subunits and the changes that occur upon protonation were modeled by the TDDFT approach. The calculated ΔGp energies for amino SBFs in the S1 state range from 985 to 1100 kJ mol−1 which are below the values for guanidines. The protonation of the guanidine-SBFs induces a hypsochromic shift of the absorption and the emission maxima with the Stokes shift of > 100 nm in both cases. Isomerization through the ESIPT process is less probable than in amino-SBFs due to the unfavorable thermodynamics. Still, if it occurs, it leads to a strong red shift of the emission by > 150 nm. Aromaticity indices point to strong antiaromatic character of the examined guanidino-SBFs in the FC region which decreases upon geometrical relaxation and ESIPT. The excited state proton transfer occurs in guanidine-SBF/phenol complexes in the S1 state, stabilizing CT states and fluorescence quenching.

Item Type:

Article

Uncontrolled Keywords:

single-benzene fluorophores; guanidines; DFT calculations; excited states; protonation transfer

Subjects:

NATURAL SCIENCES > Chemistry > Physical Chemistry
NATURAL SCIENCES > Chemistry > Organic Chemistry

Divisions:

Division of Organic Chemistry and Biochemistry

Projects: