Studies on the synthesis and fluorescent properties of long-chained 2-(5-alkyl-1, 3, 4-oxadiazol-2-yl)-3H-benzo[f]chromen-3-ones

Rajesha Rajesha,H N Harish Kumar,K M Mahadevan,H S Bhojya Naik,K M Hosamani

doi:10.3998/ark.5550190.0010.202

Abstract

The synthesis and fluorescent properties of some new benzocoumaryl heterocyclic molecules are presented. Condensation of 2-hydroxy-1-naphthaldehyde with diethyl malonate in the presence of catalytic amount of piperidine in ethanol affords benzocoumarin-3-ethyl carboxylate 2 in fairly good yield (90%). Further the compound 2 on treatment with hydrazine hydrate afforded compound 3 with excellent yield (95%). Thus compounds 4a-e have been obtained by direct cyclization of 3 with various fatty acids in the presence of POCl3. The structures of all newly synthesized compounds were confirmed by IR, 1 H NMR, 13 C NMR and UPLC-Mass spectral data. Fluorescent experimental results revealed remarkable photoluminescence properties. Luminescent properties of all newly synthesized compounds were determined and observed that they exhibited strong blue-green fluorescent properties. The fluorescence spectral properties of compounds 4a-e are similar to each other and the Stoke's shift ranges from 54 to 59 nm. Both the absorption and fluorescence maxima of the benzocoumarin-oxadiazole compounds showed good bathochromic shift.

Highlights

Fluorescent heterocyclic compounds are of immense interest as functional materials in the emitters of electroluminescence devices and in the molecular probes used for biochemical research, as well as in the traditional textile and polymer fields. 1-3 In particular, fluorescent dye materials whose fluorescence emission occur at a longer wavelength in the red light region play a leading role in full color electroluminescence displays
It is relevant to design and synthesize coumarins bearing different heterocycles at the 3-position with the aim to obtain a new photostable laser dyes having rigid structures that are tunable over a wide wavelength range within the visible spectrum
Benzocoumarins coupled with oxadiazolyl ring system are in general comparatively easy to prepare and numerous derivatives have been designed and prepared for potential use as biologically and fluorescent active materials

Summary

Introduction

Fluorescent heterocyclic compounds are of immense interest as functional materials in the emitters of electroluminescence devices and in the molecular probes used for biochemical research, as well as in the traditional textile and polymer fields. 1-3 In particular, fluorescent dye materials whose fluorescence emission occur at a longer wavelength in the red light region play a leading role in full color electroluminescence displays.

Results

Conclusion