Fluorescence from bisaryl-substituted maleimide derivatives

Abstract

A series of bisaryl-substituted fluorescent maleimides was synthesized via the Heck arylation. The compounds showed broad fluorescence emission bands in the visible region, a large Stokes shift in polar solvents and emission quantum yields varying from 0.04 to 0.71, depending on the structure and solvent medium. The difference in dipole moments of ground and excited electronic states of about 12 Debye is ascribed to a substantial charge shift and push-pull character of bisaryl-substituted maleimides. The fluorescence decays of N-benzyl-3,4-bis(4-methoxyphenyl)-1H-pyrrole-2,5-dione (compound 5a) are biexponential with short (1.3-7.6 ns) and long lived (11.5-13.6 ns) components in polar solvents, but in 1,4-dioxane and THF the decays become single exponential. On the other hand, N-benzyl-3-(4-methoxyphenyl)-4-(4-hydroxyphenyl)-1H-pyrrole-2,5-dione (compound 5b) exhibited a biexponential decay in DMSO and in DMF with much shorter decay components, and such behavior indicated a charge shift process combined with solvent assisted proton transfer in the excited state.

Development of a highly sensitive fluorescent light-up probe for G-quadruplexes

“…33,34 In addition, the nitrogen atom in the junction between the side chain and phenyl group could also be changed because the substituent connected to the chromophore sometimes influenced the fluorescence quantum yield of a compound. 35,36 Based on these considerations, we tried to modify the structure of IZCM-1, and we thereby designed a new set of disubstituted triarylimidazole fluorescent probes. As shown in Figure 1, the designed probes (IZCM-2 to IZCM-8) bear two identical substituents in comparison with IZCM-1.…”

Rational design of substituted maleimide dyes with tunable fluorescence and solvafluorochromism

“…Despite the recent advances in this field, there has been little work on varying the maleimide structures and studying the subsequent impact on their fluorescence. 8 – 13 , 21 , 34 , 35 The search for a versatile maleimide fluorophore is pivotal in this area, where structures with well-defined reactivities and varying fluorescent profiles are needed. In this work, we systemically expanded the scope of substitution patterns, through single or double substitution reactions from halogen precursors for the first time.…”

Estudo de sondas orgânicas e estratégias de marcação fluorescente de DNA: da fotoquímica básica à microscopia óptica de super-resolução

“…Therefore, the short components can be ascribed to a weak 1:1 complex between the compound and the solvent, while the long-lived components can be ascribed to a specific interaction between the excited state with push-pull character and the electron donor solvent. 112 A similar behavior was identified for compound 4a, and is discussed in paragraph 4.1.2.…”

“…4 The compounds 5b, 5c, and 5d showed similar trends. 112 Moreover, the evaluated Stokes shift is in the range of 6075 -7292 cm -1 , which is an indication that the dipole moment of these dyes is greater in the excited state than in the ground state. The spectral parameters determined under different conditions of solvent polarity are presented in Table 3.…”

“…112 The calculations were performed in collaboration with the Quantum Chemistry Group, at Institute of Chemistry of São Carlos -USP, Brazil. Changes in absorption spectra as a function of the solvent polarity were negligible.…”