Synthesis and spectral characterization of photoswitchable oligo(p-phenylenevinylene)–spiropyran dyad

Abstract

In view to design new class of photoswitchable fluorescence probes and operate them to solution as well as onto solid substrate we have envisioned the possibilities of attaching photochromic spiropyran (SP) to highly efficient fluorophore Oligo(p-phenylenevinylene)s (OPV). A new dyad SP-OPV-SP (10) was synthesized and characterised both in solution as well as film onto solid substrate where two SP units as photochromic acceptors are attached to the two ends of OPV, a fluorescent donor. External stimulations ( ultraviolet light,visible light and acid) generate reversible changes of the structure resulting the changes of absorption spectrum and fluorescence emission spectra of dyad 10 due to the presence of two spiropyran units. Photoinduced (ultraviolet light) isomerization of the spiropyran causes 60% decrease in the emission intensity of the OPV at the photostationary state in solution of 60 µM concentration. In solid state, ultraviolate irradiation causes~98% reduction of fluorescence intensity of OPV. The photogenerated isomer is quite more stable in solid state than that in solution. The fluorescence intensity of dyad 10 is modulated by reversible conversion among the three states of the photochromic spiropyran units and the fluorescence resonance energy transfer (FRET) between the MC form of SP and the OPV unit. In any case, these investigations demonstrate that design of dyad 10 is viable for the realization of photoswitchable molecular assemblies and can evolve as efficient fluorescent probes for potential applications towards molecular device design like integrated logic gate with multiple inputs and single output.

Ultrafast Fluorescence Photoswitch Incorporating Diketopyrrolopyrrole and Benzo[1,3]oxazine

“…In the light of structural implications in the isomerization mechanism of spiropyran, − we realized that the introduction of an appropriate photochrome will offer the opportunity to implement an ultrafast photochromic transformations. Keeping this in mind, we have designed ultrafast photochromic unit, OX­(5) (Figure ) synthesized from 2,3,3-trimethyl-3 H -indole, 4-formyl benzoic acid, and 2-chloromethyl-4-nitrophenol compounds in three steps.…”

“…The fluorescence switching materials allowing us to photoinduced interconversion of photochromic units − with distinct absorption spectra under the influence of optical stimulations are exploited to modulate the emission of complementary fluorophores. − In fact, their use as fluorescent probes has already been explored by us with typical examples. , In the wake of these promising results, we designed a photochrome-fluorophore-photochrome dyad (Chart ) incorporating fluorescent diketopyrrolopyrrole (DPP) component, which emits at 570 nm upon excitation at 500 nm (λ ON ), and a photochromic spiropyran (SP) component, which switches to the corresponding merocyanine (i.e., MC, open conformer) upon irradiation at 330 nm (λ OFF ). The very fast photoinduced transformation of SP into MC (32 ps) encourages the energy transfer pathways (FRET), which induced effective quenching of the DPP fluorescence.…”

Wide-gamut lasing from a single organic chromophore

“…1,4-bis(bromomethyl)−2,5-bis(neopentyloxy) benzene (2) was synthesized via a Blanc-type bromomethylation of 1, similar to a recently described procedure 53 . Compound 1 (3.82 g; 15.26 mmol; 1.0 eq.)…”

Extended isoindigos as building blocks for developing D–A-type conjugated polymers

“…n-Tetradecylindolin-2-one (2) is synthesized according to the reported literature process. [54][55][56] Dialdehyde 4 is synthesized from 1,4-dihydroxybenzene according to the literature procedure reported by Doddi et al 57 The p-extended isoindigo derivatives with p-dimethylenebenzene, dialkoxy-p-dimethylenebenzene and 2,5-dimethylenethiophene as the central spacer (3, 5 and 7) are synthesized by Knoevenagel condensation 58 between n-tetradecylindolin-2-one (2) and the corresponding dialdehydes (1, 4 and 6) using piperidine as a base (Scheme 1). D-A-type p-conjugated polymers are synthesized via C-C coupling reaction in which the 5,5 0 -bis(trimethylstannyl)-2,2 0bithiophene unit is coupled with p-extended isoindigo compounds 3, 5 and 7 using Pd 2 (dba) 3 and tri-o-tolylphosphine as the catalyst-ligand system in refluxing toluene (Scheme 2).…”