Excited-State Intramolecular Proton Transfer Distinguishes Microenvironments in Single- And Double-Stranded DNA

Abstract

Herein, the efficient interaction of an environment-sensitive fluorophore that undergoes excited-state intramolecular proton transfer (ESIPT) with DNA has been realized by conjugation of a 3-hydroxychromone (3HC) with polycationic spermine. On binding to a double-stranded DNA (dsDNA), the ratio of the two emission bands of the 3HC conjugates changes up to 16-fold, so that emission of the ESIPT product increases dramatically. This suggests an efficient screening of the 3HC fluorophore from the water molecules in the DNA complex, which is probably realized by its intercalation into dsDNA. In sharp contrast, the 3HC conjugates show only moderate changes in the dual emission on binding to a single-stranded DNA (ssDNA), indicating a much higher fluorophore exposure to water at the binding site. Thus, the 3-hydroxychromone fluorophore being conjugated to spermine discriminates the binding of this polycation to dsDNA from that to ssDNA. Consequently, ESIPT-based dyes are promising for monitoring the interaction of polycationic molecules with DNA and probing the microenvironment of their DNA binding sites.

ESIPT reaction of potential bioactive heterocyclic Schiff base: Atomic visualization coupled with in vitro spectroscopy

“…Photoinduced electron transfer and proton transfer are important fundamental processes for many biochemical reactions and find numerous applications in scientific field [1][2][3][4][5][6][7][8][9][10][11][12][13]. Amongst all the photoinduced processes, excited state proton transfer are of special interest.…”

A quantum-chemical insight into the tunable fluorescence color and distinct photoisomerization mechanisms between a novel ESIPT fluorophore and its protonated form

“…Owing to such important applications, organic dyes undergoing ESIPT continue to receive wide attention from the experimental and theoretical aspects [1,[22][23][24][25][26][27][28][29][30][31][32][33][34]. Recently, Sakai et al reported the synthesis and comprehensive optical properties of a novel ESIPT fluorophore bearing the imidazole (Im) and benzothiazole (BT) moieties, 2-(1,3-benzothiazol-2-yl)-4-methoxy-6-(1,4,5-triphenyl-1H-imidazol-2-yl)phenol (BTImP) [1].…”

TDDFT Assessment of Excited State Intramolecular Proton Transfer in a Panel of Chromophore 2-Hydroxypyrene-1-Carbaldehyde

“…Ever since the seminal experimental observation of the excited-state intramolecular proton transfer (ESIPT) reaction of methyl salicylate (MS) by Weller et al in the middle of the last century [1], the phenomenon of photoinduced proton transfer process has attracted countless works in many fields of chemistry and molecular biology [2][3][4][5][6][7][8][9][10][11][12][13][14][15]. A very fascinating feature of molecules undergoing ESIPT is the presence of a strong intramolecular hydrogen bond, in which the acidity and basicity relations can be controllable by photoexcitation.…”