Poly(aryl ether) Dendrons with Monopyrrolotetrathiafulvalene Unit‐Based Organogels exhibiting Gel‐Induced Enhanced Emission (GIEE)

Abstract

A series of poly(aryl ether) dendrons with a monopyrrolo-tetrathiafulvalene unit linked through an acyl hydrazone linkage were designed and synthesized as low molecular mass organogelators (LMOGs). Two of the dendrons could gelate the aromatic solvents and some solvent mixtures, but the others could not gel all solvents tested except for n-pentanol. A subtle change on the molecular structure produces a great influence on the gelation behavior. Note that the dendrons could form the stable gel in the DMSO/water mixture without thermal treatment and could also form the binary gel with fullerene (C60 ) in toluene. The formed gels undergo a reversible gel-sol phase transition upon exposure to external stimuli, such as temperature and chemical oxidation/reduction. A number of experiments (SEM, FTIR spectroscopy, (1) H NMR spectroscopy, and UV/Vis absorption spectroscopy, and XRD) revealed that these dendritic molecules self-assembled into elastically interpenetrating one-dimensional fibrillar aggregates and maintain rectangular molecular-packing mode in organogels. The hydrogen bonding, π-π, and donor-acceptor interactions were found to be the main driving forces for formation of the gels. Moreover, the gel system exhibited gel-induced enhanced emission (GIEE) property in the visible region in spite of the absence of a conventional fluorophore unit and the fluorescence was effectively quenched by introduction of C60 .

Augmenting Photoinduced Charge Transport in a Single‐Component Gel System: Controlled In Situ Gel–Crystal Transformation at Room Temperature

“…Therefore, extending this concept to any potential application is hitherto unknown. Unlike molecular gelators having traditional long alkyl chains, the structural uniqueness of acyl hydrazine‐linked lower generation of poly(aryl ether) (PAE) dendrons (Frèchet type) can pre‐program the molecular self‐assembly to well‐control the desired maximal electronic coupling of o ‐benzoxy rings, driven through H‐bonding interactions . Despite being used for diverse applications in soft matter research, the optoelectronic response of novel poly(aryl ether) dendron‐based gel systems remains untouched till date.…”

“…Unlikem olecular gelators having traditionall ong alkyl chains, the structural uniquenesso fa cyl hydrazine-linked lower generationo fp oly-(aryl ether) (PAE) dendrons (Frchet type) can pre-program the molecular self-assembly to well-controlt he desired maximal electronic coupling of o-benzoxyr ings, drivent hrough Hbondinginteractions. [18][19][20][21] Despite being used for diverse applicationsi ns oft matterr esearch, the optoelectronic response of novelp oly(aryl ether)d endron-based gel systems remains untouched till date. Arylamines, for example, triphenylamine (TPA) derivatives suffer from knotty aggregationc aused quenching of luminescence, albeit being an exceptionally well hole-transporting species.…”

Charge Transfer Modulated Self-Assembly in Poly(aryl ether) Dendron Derivatives with Improved Stability and Transport Characteristics

“…While poly­(aryl ether) dendron derivatives are known for forming robust self-assembled systems, the role of charge transfer in stabilizing supramolecular assembly of poly­(aryl ether) dendron derivatives has not been evaluated. Recently, Yin and co-workers reported functionalized TTF (tetrathiafulvalene) appended PAE dendron (donor) based gels, where inclusion of fullerene C 60 (acceptor) resulted in the formation of a binary gel but without any CT interactions …”

“…Recently, Yin and co-workers reported functionalized TTF (tetrathiafulvalene) appended PAE dendron (donor) based gels, where inclusion of fullerene C 60 (acceptor) resulted in the formation of a binary gel but without any CT interactions. 31 The objective of the present study is to develop poly(aryl ether) dendron based gel systems with high charge-transfer (CT) characteristics and understand the role of CT interactions in modulating the functional properties of the gel using experimental and theoretical methods. Chart 1 represents the molecular structures of the respective donor and acceptor molecules used in the present study for gelation.…”

“…The self-assembly of a highly flexible lower generation of poly­(aryl ether) dendrons (Frèchet type) with acyl hydrazone linkage can be well controlled to achieve the desired nanoscale morphology. − This shows their ability to preprogram the molecular self-assembly as well as to maximize the electronic coupling by means of extensive π-stacking driven via H-bonding interactions. Unlike molecular gelators having conventional long alkyl chains, they are easy to synthesize and offer a precisely well-defined largely branched unique molecular architecture for self-assembled supramolecular gel phase materials forming a 3D network of 1D fibers. − Previous studies from our group and others have shown that novel poly­(aryl) ether dendrons develop efficient organogelators which can be used for gelation induced enhanced emission (GIEE), redox response and sensing, white light emission, and multifunctional applications. − All of these properties along with the recently reported fascinating gel phase multicolor emission and gelation promoted excited state induced proton transfer (ESIPT) coupled AIEE phenomena make poly­(aryl ether) (PAE) dendrons an extremely novel candidate for versatile applications. − Despite their use in all of these captivating areas, the electrical properties of PAE dendron based self-assembled molecular materials are yet to be investigated. Aiming at the use of novel PAE dendron based gels in organic electronics, we have developed for the first time, PAE dendron based charge transfer gels mediated via donor–acceptor interactions and native gels formed by H-bonding and π···π interactions, resulting in the formation of conductive materials.…”