D-π-A-A-π-D Prototype 2,2′-Bipyridine Dyads Exhibiting Large Structure and Environment-Sensitive Fluorescence: Synthesis, Photophysics, and Computation

Abstract

A series of 4,4'-π-conjugated-2,2'-bipyridine chromophores (MS 1-8) were synthesized, and their photophysical and thermal properties were investigated. The title "push-pull' chromophores", except MS 1, were integrated with both alkoxy and alkylamino donor functionalities that differ in their donation capabilities. The oligophenylenevinylene (OPV) chromophores MS 4-8 are associated with a π-extended backbone in which the position and the number of alkoxy donors were systematically varied. All of the studied systems possess a D-π-A-A-π-D dyad archetype in which the A-A is the central 2,2'-bipyridine acceptor core that is electronically attached with the donor termini through π-linkers. The fluorescence quantum yields of the synthesized chromophores are found to be sensitive to the molecular archetype and the solvent medium. Out of the eight fluorescent compounds reported in this article, the compound MS 5 exhibits fluorescence in the solid state also. The modulating effect of the nature, position, and number of donor functionalities on the optical properties of these classes of compounds has further been comprehended on the basis of DFT and TD-DFT computation in a solvent reaction field.

Dipyrido[3,2‐a:2′,3′‐c]phenazine‐Based Donor–Acceptor Aromatic Heterocyclic Compounds with Thienyl and Triphenylamino Chromophores at the 2,7‐ and/or 10,13‐Positions

“…[31] In this work, ten aromatic heterocyclic compounds have been checked by thermogravimetric analysis (TGA), and a parameter of Td 10 (10 % weight-loss temperature) was used to describe the thermal stability of these compounds. As illustrated in Figure 4, the TGA curves of 6,8,10,11,13, and 15 indicate that they can remain unchangeable when the temperature is below 500 8C and the Td 10 values for them are found to range from 524 to 646 8C, which should be one of the best results for the thermal stability for organic small molecules.…”

Synthesis and Electrochemical and Photophysical Characterization of New 4,4′‐π‐Conjugated 2,2′‐Bipyridines that are End‐Capped with Cyanoacrylic Acid/Ester Groups

“…Such light‐harvesting systems typically comprise a photosensitizer dye and a metal‐oxide or electron acceptor molecule, which show strong absorption cross‐sections in a wide range of the visible spectrum, as well as sufficiently high LUMO energies to allow efficient electron‐transfer reactions to the acceptor (the metal‐oxide semiconductor conduction band or the HOMO of the molecular electron acceptor). Strongly fluorescent dyes based on nitrogen‐containing heterocycles (e.g., pyridines) are commonly employed as photosensitizer building blocks, because of their ease of synthesis; moreover, derivatization of the pyridine ring allows fine‐tuning of the optical and electronic properties of the building blocks, as well as attaching anchoring groups for linking to metal‐oxide surfaces …”

“…These systems absorb light through intramolecular charge transfer (ICT) and emit from the corresponding photoexcited state . Moreover, bipyridine‐, terpyridine‐, or phenanthroline‐based π‐extended compounds are widely used as ligands in metal complexes (Figure ), which are used in electrochemical applications, in particular in light‐emitting diodes or as dyes for dye‐sensitized solar cells (DSSCs) . These ligands enable the fine‐tuning of the photophysical and electrochemical properties of the complexes by influencing the metal‐to‐ligand charge transfer (MLCT) process …”

Study on Synthesis and Fluorescence of Novel Benzofused Phenazine π-Conjugated Skeleton with Coumarin and Isophoron Cores

“…In recent years, the development of organic π-conjugated molecules for organic electronic, such as organic light emitting diode (OLEDs) [1], organic field effect transistor (OFETs) [2], environment-sensitive fluorescence [3] and organic photovoltaic (OPVs) [4] remain a key objective. Organic materials have distinct advantage of their structure diversity, which can be achieved by versatile synthetic protocol in organic chemistry.…”