Three-Component Suzuki–Knoevenagel Synthesis of Merocyanine Libraries and Correlation Analyses of Their Oxidation Potentials and Optical Band Gaps

Tim Meyer,Thomas J J Müller,Roxanne Krug

doi:10.3390/molecules26175149

Three-Component Suzuki–Knoevenagel Synthesis of Merocyanine Libraries and Correlation Analyses of Their Oxidation Potentials and Optical Band Gaps

Tim Meyer, Thomas J J Müller + Show 1 more

Open Access

https://doi.org/10.3390/molecules26175149

Copy DOI

Abstract

The Suzuki coupling Knoevenagel condensation one-pot synthesis of boronic acids/esters, (hetero)aromatic bromo aldehydes and methylene active compounds is a highly practical consecutive three-component process to provide substance libraries with 60 donor-π-bridge-acceptor molecules, i.e., merocyanines in a broader sense, in moderate to excellent yield. As already seen with the naked eye, a broad variation of the optical properties becomes accessible using this practical synthetic tool. More systematically, correlation analyses upon plotting the optical band gaps against the first oxidation potentials of redox active systems of consanguineous series furnishes linear correlations and, by extension, two parameter plots (oxidation potential and emission maximum) planar correlations with the optical band gaps.

Highlights

Multicomponent reactions (MCR) [1–4], conducted in domino, sequential or consecutive fashion, represent a powerful, efficient and efficacious tool for constructing complex molecular scaffolds in a one-pot fashion
In a very general sense, merocyanines can be structurally characterized as donor-π-bridgeacceptor scaffolds with high extinction coefficients, and as chromophores they are omnipresent in optoelectronics [14–17], organic semiconductors [18] and organic photovoltaics (OPV) [19]
Suzuki arylation and Knoevenagel condensation in a consecutive three-component substance libraries nating of dyes for establishing structure-property relationships based upon fashion can be favorable for accessing substance libraries of dyes for establishcorrelation analysising (Scheme structure-property relationships based upon correlation analysis (Scheme 1)

Summary

Introduction

Multicomponent reactions (MCR) [1–4], conducted in domino, sequential or consecutive fashion, represent a powerful, efficient and efficacious tool for constructing complex molecular scaffolds in a one-pot fashion. We have developed and explored MCRs as concise entries to functional chromophores. For fluorophores and electrophores [5–7], MCRs are most fruitfully applied in the sense of a chromogenic approach, which results directly in the formation of the functional chromophore of interest. In a very general sense, merocyanines can be structurally characterized as donor-π-bridgeacceptor scaffolds with high extinction coefficients, and as chromophores they are omnipresent in optoelectronics [14–17], organic semiconductors [18] and organic photovoltaics (OPV) [19]. Due to their inherent dipolar nature, the self-assembly of merocyanines in solution even allows for concise access to nanoscale objects and supramolecular materials [20,21]. The classical synthesis of merocyanines, as for many polymethine dyes, is governed by conventional aldol or Knoevenagel condensations [8,22–24]

Methods

Results

Conclusion