Synthesis, electrochemistry, and photophysical properties of pyrazolino[60]fullerene–1,8-naphthalimide fluorescent derivatives

Rational Design of Push-Pull Fluorene Dyes: Synthesis and Structure-Photophysics Relationship

Our work surveyed experimental and theoretical investigations to construct highly emissive D-π-A (D=donor, A=acceptor) fluorenes. The synthetic routes were optimised to be concise and gram-scalable. The molecular design was first rationalised by varying the electron-withdrawing group from an aldehyde, ketotriazole or succinyl to methylenemalonitrile or benzothiadiazole. The electron-donating group was next varied from aliphatic or aromatic amines to saturated cyclic amines ranging from aziridine to azepane. Spectroscopic studies correlated with TD-DFT calculations provided the optimised structures. The selected push-pull dyes exhibited visible absorptions, significant brightness, important solvatofluorochromism, mega-Stokes shifts (>250 nm) and dramatic shifts in emission to the near-infrared. The current library includes the comprehensive characterization of 16 prospective dyes for fluorescence applications. Among them, several fluorene derivatives bearing different conjugation anchors were tested for coupling and demonstrated to preserve the photophysical responses once further bound.

An efficient comparison of methods involving conventional, grinding and ultrasound conditions for the synthesis of fulleroisoxazolines

In this research, an efficient comparison between conventional, grinding and sonication methods for the synthesis of fulleroisoxazolines was investigated. Compared to the conventional methods, ultrasound procedure showed several advantages including mild reaction conditions, high yields, short reaction times and environmental friendliness.

Modification of fulleropyrazolines modulates their cleavage by light

The extraordinary electrochemistry and the tunability of their energy levels allows the use of fulleropyrazolines in photovoltaics and charge-transfer systems. Here we show that substitution in position 1 tunes photolytic stability; electron-donating groups facilitate 1,3-dipolar cycloreversion to fullerene. This discovery has implications not only for photovoltaic stability but also highlights a potential strategy for photo-controlled fullerene release systems ('photo-caged'/'photo-activated' fullerene).

In situ Bronsted-Lowry acid catalyzed syntheses, characterization, single crystal XRD, electronic spectral-, DPPH radical scavenging-, and DNA protection studies of aryl-3,3'-bis(indolyl)methanes

A series of novel aryl-3,3'-bis(indolyl)methanes (BIMs) were synthesized using indole and formylphenoxyaliphatic acid(s) in water in the absence of any catalyst. The formylphenoxyaliphatic acid behaves as an in situ Bronsted-Lowry acid catalyst in water. UV-Visible and fluorescence spectra of the compounds were recorded in selected solvents. The gas phase geometry optimization of the compounds were achieved using DFT calculations at B3LYP/3-21G((*)) level of theory. The electronic properties, such as HOMO-LUMO energies were calculated using the above method based on the optimized structure. Compounds have better DPPH radical scavenging activity and reduction of oxidative damage of DNA.