Heterocyclic Quinol‐Type Fluorophores: Synthesis, X‐ray Crystal Structures, and Solid‐State Photophysical Properties of Novel 5‐Hydroxy‐5‐substituent‐benzo[b]naphtho[1,2‐d]furan‐6‐one and 3‐Hydroxy‐3‐substituent‐benzo[kl]xanthen‐2‐one Derivatives

Abstract

Novel heterocyclic quinol-type fluorophores (4 a-c) and (5 a-c) that contain substituents (R = Me, Bu, Ph) with nonconjugated linkages to the chromophore skeleton have been synthesized and their photophysical properties have been investigated in solution and in the solid state. Considerable differences in the absorption and fluorescence spectra were observed between the two states. Quinols 4 a-c and 5 a-c exhibited almost the same absorption and fluorescence spectra in solution; however, their solid-state fluorescence excitation and emission spectra in the crystalline state were quite different. We performed X-ray crystallographic analyses to elucidate the dramatic effect of the substituents of the nonconjugated linkage on the solid-state fluorescence excitation and emission spectra. The relationships between the solid-state photophysical properties and the chemical and crystal structures of 4 a-c and 5 a-c are discussed on the basis of the X-ray crystal structures.

Synthesis and Characterization of Far‐Red/NIR‐Fluorescent BODIPY Dyes, Solid‐State Fluorescence, and Application as Fluorescent Tags Attached to Carbon Nano‐onions

“…All of these approaches modify the BODIPY molecular structure to suppress π–π stacking of the BODIPY building blocks in the solid state. This general concept has also been reported for other fluorophores 23. 24…”

Heterocyclic Quinol‐Type Fluorophores: Solid‐State Fluorescence Change in Crystals of Benzo[b]naphtho[1,2‐d]furan‐6‐one‐Type Fluorophore upon Inclusion of Organic Solvent Molecules

“…[7] Here, we report sensitive colour and fluorescence change of the quinol 1 upon enclathration of organic solvent molecules in the solid state. The X-ray crystal structures of 1 and its guest-inclusion compounds have been determined, on the basis of which the enclathrated guest effects on the solid-state fluorescence properties are discussed.…”

“…A large red-shift of the absorption and fluorescence maxima and the solid-state fluorescence quenching by strong donor-acceptor type π-π interactions of fluorescent dyes are known. [4][5][6][7][8][9][10] In fact, the fluorescence emission intensities of 1a-1c are in the order of 1c>1b>1a in the crystalline state. In the crystal of 1b, a donor-acceptor type of π-stacking between a pair of quinol enantiomers is observed, however, the rang of the π-stacking is less than that of 1a.…”

Crystallization of thiophene/phenylene co-oligomers by dropping of their solutions into poor solvents

“…Furthermore, their dense packing of molecules leads to excellent robustness [1]. There have been a number of reports on the characteristics of organic materials in their crystalline phase [2][3][4]. Among these compounds, thiophene/phenylene co-oligomer (TPCO) consisting of thiophene and benzene rings exhibits excellent performance for light emission and electronic mobility [5].…”