Charge transfer complexes as colour changing and disappearing–reappearing colour materials

Abstract

Charge transfer complexes, made of suitably chosen electron-rich and electron-deficient components, can perform as vanishing colour, disappearing–reappearing colour and colour changing materials.

Interplay of π-stacking and inter-stacking interactions in two-component crystals of neutral closed-shell aromatic compounds: periodic DFT study

“…The stacking motif of these crystals carries over to asymmetric units made of a heterodimer. 29 Charge-transfer complexes, for example, 1,3,5-trinitrobenzene cocrystals, 6 are beyond the scope of the study.…”

“…5 There is much debate about the nature of pstacking interactions. 6 Different classes of tools were developed to translate the results of quantum computations into intuitively useful concepts, which appeal to chemists. 7 Symmetryadapted perturbation theory (SAPT) 8 (Table S1); the traceless quadrupole moment components of the substituted aromatic and heterocyclic molecules, which are acceptors in two-component crystals (Table S2); the distance between the centers of mass of the molecules R and the quadrupole-quadrupole interaction energy U Q 1 Q 2 of stacked heterodimers C 6 F 6 /C n H m and C 10 F 8 /C n H m which structure was fully relaxed in non-periodic computations (Table S3); the values of the electron density r b and its Laplacian V 2 r b at intermolecular bond critical points of crystalline naphthalene evaluated in the present study vs. the literature data (Table S4); the intermolecular interactions in crystalline naphthalene with the corresponding bond critical points (Fig.…”

“…12 Fourth, only p-stacking interactions are considered in nonperiodic calculations, while inter-stacking interactions play a structure-forming role. 29 Finally, a variety of systems was considered, namely: neutral closed-shell aromatic and heteroaromatic compounds, 30 charge-transfer complexes, 6 systems consisting of a charged molecule 37 or a molecule in the electronically excited state, 38 and metal complexes with aromatic ligands. 39 Obviously, the electrostatic contribution to the pstacking energy in such systems is caused by interactions of various types (Coulomb, dipole-dipole, etc.).…”

“…40 There are numerous two-component (binary) crystals composed of two organic compounds unable to form conventional hydrogen bonding. 5,6,29,30,34 The association modes mostly include stacking of at systems, one of them usually being an aromatic hydrocarbon, e.g. arene.…”

Combined X-ray Crystallographic, IR/Raman Spectroscopic, and Periodic DFT Investigations of New Multicomponent Crystalline Forms of Anthelmintic Drugs: A Case Study of Carbendazim Maleate

“…However, most crystals with actual or potential practical application have little in common with the structures from the benchmark sets. Some examples include single-component crystals of larger, conformationally flexible molecules [10][11][12][13][14], fluoroorganic compounds [15,16], and multicomponent crystals [17][18][19], often with short (strong) [20,21] or ionic H-bonds [22]. The applicability of the methods tested against the benchmark sets for modeling the properties of non-model crystals (e.g., organic salts) is unclear.…”