[2 + 2]Photocyclization in a single-crystal-to-single-crystal transformation of a TTF-amido-pyridine

Abstract

The redox active ligand EDT-TTF-CONH-3-pyridine undergoes a [2 + 2] cycloaddition upon irradiation with polychromatic light, an unprecedented single-crystal-to-single-crystal transformation for a TTF derivative.

Fluorine Segregation in Crystalline Materials: Structural Control and Solid‐State [2+2] Cycloaddition in CF3‐Substituted Tetrathiafulvalene Derivatives

“…This [2+2] photocyclization is similar to that observed upon irradiation of carbamoyl tetrathiafulvalenes [47,48] as well as an amidopyridyl tetrathiafulvalene formulated as EDT-TTF-CONH(3-Py) [49] where a single-crystal-to-singlecrystal transformation was revealed due to a favorable orientation of the molecules through p-p interactions. Following the pioneering work of Schmidt on the [2+2] photodimerization of cinnamic acids, [50] several geometrical rules have been established as guidelines for evaluating the possible occurrence of such dimerizations.…”

Reversible single crystal-to-single crystal double [2+2] cycloaddition induces multifunctional photo-mechano-electrochemical properties in framework materials

“…This likely arises from a small proportion of the uncyclised cofacial form still present in the framework, as the removal of conjugation from the TTF core in 3 reduces the ability for electron delocalisation, which stabilises the oxidation states accessible to Py 2 TTF. The assignment of the irreversible oxidation at 0.83 V (vs. Fc/Fc + ) cannot definitively be identified, but the process is consistent with the reported electrochemical behaviour of a one-sided [2 + 2] photocyclised TTF based molecule 31 . This intermediate state, however, does demonstrate that the degree of cyclisation of the material can be used to control the material's electrochemical properties.…”

“…Despite the numerous examples of TTF-based complexes and framework materials that fulfil these criteria, only five examples of complexes have been crystallographically shown to undergo photo-dimerisation, all of which occur on only one side of the TTF core [31][32][33][34][35] . The ability for this material to undergo double photocyclisation likely arises from the framework providing geometrical constraints to fulfill Schmidt's criteria, while also exhibiting flexibility to respond to the structural change.…”

Supramolecular isomerism in multivalent metal-templated assemblies with topochemical influence in the regioselective synthesis of tetrakis(2-pyridyl)cyclobutane isomers

“…Covalent synthesis performed in the solid state is considered an important alternative for the preparation of new and conventional compounds. [1][2][3] In particular, the topochemical [2 + 2] cycloaddition of olefins represents an interesting route for the preparation of multitopic organic molecules. Such compounds are very attractive as tectons for the design of unusual supramolecular metal assemblies.…”