Abstract
Covalent donor-acceptor (D-A) systems have significantly contributed to the development of many organic materials and to molecular electronics. Tetrathiafulvalene (TTF) represents one of the most widely studied donor precursors and has been incorporated into the structure of many D-A derivatives with the objective of obtaining redox control and modulation of the intramolecular charge transfer (ICT), in order to address switchable emissive systems and to take advantage of its propensity to form regular stacks in the solid state. In this review, we focus on the main families of non-fused TTF-acceptors, which are classified according to the nature of the acceptor: nitrogen-containing heterocycles, BODIPY, perylenes and electron poor unsaturated hydrocarbons, as well as radical acceptors. We describe herein the most representative members of each family with a brief mention of their synthesis and a special focus on their D-A characteristics. Special attention is given to ICT and its modulation, fluorescence quenching and switching, photoconductivity, bistability and spin distribution by discussing and comparing spectroscopic and electrochemical features, photophysical properties, solid-state properties and theoretical calculations.
Highlights
Covalent donor–acceptor systems have long attracted significant interest due to their involvement in electron transfer processes in biology[1,2,3] and as they constitute valuable precursors forOne of the most important electron donors, especially in the field of molecular materials, is the tetrathiafulvalene (TTF) unit,[5] which has provided many organic metals and superconductors[6] and, more recently, multifunctional materials combining conductivity and magnetism,[7] conductivity and chirality,[8] or based on luminescent single molecule magnets[9] or electroactive ligands and metal complexes.[10]
The first TTF–PDI derivatives were reported by Zhang and Zhu et al within triads, such as 53.89 It has been shown that the two electroactive units behave completely independently, as the oxidation potentials to TTF+ and TTF2+ and the reduction potential of PDI, which is strongly anodically shifted compared to perylene in 51–52 (Table 7), have exactly the same values as for the separated reference compounds
We reviewed the main families of nonfused TTF–acceptors reported in the literature since 2004, when the previous extensive review on this topic was published,[11] with a special focus on their specific properties, such as electronic communication between the units, intramolecular charge transfer and its modulation by protonation, coordination, solvent, modulation of the emission properties and quenching mechanisms, photo-activated conductivity, control of the spin distribution, etc
Summary
One of the most important electron donors, especially in the field of molecular materials, is the tetrathiafulvalene (TTF) unit,[5] which has provided many organic metals and superconductors[6] and, more recently, multifunctional materials combining conductivity and magnetism,[7] conductivity and chirality,[8] or based on luminescent single molecule magnets[9] or electroactive ligands and metal complexes.[10]. II mixed valence species thanks to communication through the TTF bridge Across this short historical saga of TTF–TCNQ, we wanted to point out a very illustrative scientific process, originating from a hypothesis that evolved towards other numerous other directions, constituting the molecular electronics field,[24] and motivated an enormous amount of experimental work[25] that eventually provided several covalent TTF–TCNQ systems. We focus on several recent representative families of non-fused covalently linked TTF–acceptors, classified according to the chemical nature of the acceptor, with an aim to highlight some of their most peculiar features
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
