Photoinduced Electron Transfer in Covalently Linked 1,8-Naphthalimide/Viologen Systems

Abstract

A series of polymethylene-linked 1,8-naphthalimide/viologen diads has been synthesized. The number of intervening methylenes was varied from 2 to 6. For comparison, a series of N-alkylpyridiniumyl-1,8-naphthalimide “parent” compounds was prepared and photophysically characterized. Relative to the parent compounds, the electronically excited singlet state of the 1,8-naphthalimide was found to be quenched by the covalently attached viologen. From Stern−Volmer analyses of the steady-state fluorescence spectra, along with the singlet-state lifetime of the pyridinium-substituted 1,8-naphthalimide, the rate constants for intramolecular quenching were calculated to range from 1.5 × 1010 s-1 (2 intervening methylenes) to 8.3 × 107 s-1 (6 intervening methylenes) in aqueous buffered solution. For comparison, the intermolecular reactivity of the excited singlet state of N-alkylpyridiniumyl-1,8-naphthalimides with methylviologen was assessed. In 0.5 M phosphate buffer (pH 7.0), the bimolecular rate constant was found to be 3.2 × 109 M-1 s-1. Nanosecond laser flash photolysis studies were carried out to identify the quenching products. From these studies, reduced methylviologen was identified as a singlet-state quenching product. From these results, we attribute both the intra- and intermolecular quenching process to electron transfer from the singlet excited state of 1,8-naphthalimide to methylviologen. Within the covalently linked series, the rate constant for intramolecular electron transfer was found to vary exponentially with the number of intervening methylenes. Linear least-squares analysis of the results yielded an apparent β value of 1.04 Å-1 for electron transfer through the polymethylene bridge.

Synthesis, Optical Characteristics and Complex Formation of Molecular Receptors Based on 1,8-Naphthalimide Derivatives in Solution and in Composition of Hybrid Tin Dioxide Nanoparticles

“…After the reaction mixture was cooled to room temperature, the catalyst was filtered off, the filtrate was evaporated in vacuo. The residue was purified by column chromatography (silica gel, eluent PhH-EtOH, gradient elution) to yield 23 mg (16 % (1) 6-(2- (2,3,5,6,8,9,11, [1,4,10,7,13] …”

“…Among the large arsenal of modern physical and chemical methods of analysis the optical spectroscopy has huge popularity, [1] which is primarily due to the relative simplicity of the experiment coupled with a high sensitivity with respect to detectable substrates. In the past two decades, much progress has been achieved due to the development of optical chemosensors containing a selective receptor, and a signaling moiety capable of changing its spectral characteristics as a result of complex formation.…”

Fluorescent monolayer protected gold nanoparticles – Preparation and structure elucidation

“…The reaction was carried out selectively in refluxing absolute EtOH, avoiding participation of the aromatic bromine [20,21]. After column chromatography the pure 1,8-naphthalimide 3 was isolated and in the second step refluxed with NaOMe in absolute methanol to substitute the aromatic bromine atom of 3 with methoxy group [22], without catalyst.…”

Intra- and Interlayer Energy Transfer in Planar Systems Based on Amphiphilic Naphthalimide Derivatives

“…[7] Фотофизические свойства производных нафтали-мида привлекают значительное внимание исследовате-лей не только благодаря своим функциональным харак-теристикам. Наличие у нафталимидного ядра электроно-акцепторных свойств в возбужденном состоянии делает эти соединения удобными моделями для изучения распространенных в живой природе процессов фотоин-дуцированного переноса электрона, [8,9] а также процес-сов безызлучательного резонансного переноса энергии электронного возбуждения по механизму Г. Фёрстера (Forster Resonance Energy Transfer, FRET). [10][11][12][13][14][15][16] В связи с этим большой интерес представляют возможности исследования механизмов FRET-процессов, открываю-щиеся при использовании модельных бисхромофорных систем, состоящих из высокоорганизованных мономоле-кулярных слоев соединений данного типа, с контролиру-емыми условиями сборки.…”