Guest-Binding-Induced Interhetero Hosts Charge Transfer Crystallization: Selective Coloration of Commonly Used Organic Solvents

Abstract

Unprecedented interheteromacrocyclic hosts charge transfer (CT) crystals were generated by cooling organic solutions containing p-dimethoxybenzene-constituted pillar[5]­arene (P5A) and p-benzoquinone-constituted pillar[5]­quinone (P5Q). Despite the weak CT interaction known between p-dimethoxybenzene and p-benzoquinone and the lack of formation of CT complexes between P5A and P5Q in the solution phase, CT cocrystals between P5A and P5Q were formed with solvent molecules included into the hosts’ cavities. Such a cocrystallization arises from an elegant synergy between the CT interaction and solvent-binding-promoted crystallization. The interhetero hosts CT crystals were studied by optical and electron microscopic techniques, X-ray powder diffraction, solid-state NMR, UV–vis, IR spectroscopic studies, and X-ray single-crystal studies. The solvent complexation was critical for formation of the supramolecular CT microcrystals. The CT absorption bands faded upon removing the solvent molecules under vacuum, but they could be recovered by reuptake of the solvent molecules. Intriguingly, the CT absorption bands and uptake kinetics are distinguishably different for various organic solvents, thus providing a unique way to distinguish between different commonly used chemicals.

Solvent-Driven Chirality Switching of a Pillar[4]arene[1]quinone Having a Chiral Amine-Substituted Quinone Subunit

“…The UV-vis spectra of chiral amine-substituted pillar[4]arene[1]quinones were measured in chloroform at 25°C. EtP4Q1 showed a sharp absorption peak at 294 nm and a broad absorption at the visible range ( Figure 1 ), assignable to the transitions of hydroquinone ether units and the intramolecular charge transfer, respectively ( Mi et al, 2020 ; Mi et al, 2021 ). The UV-vis spectra of the mono-substituted pillar[4]arene[1]quinone derivatives 1b and 2b exhibited two major transitions, showing a weak broad absorption that tailed to 400–700 nm, which is assignable to a CT transition.…”

Multicomponent Molecular Assembly of Fluorescent Organic Semiconductors Beyond Three Compounds

“…[26,27] Homogeneous binary mixtures involving organic cocrystals and alloys can be considered to be highly miscible in which two constituent molecules are held together in a periodically arranged manner or in a randomly mixed fashion. [28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44] Binary organic cocrystals were commonly obtained by weak noncovalent interactions involving hydrogen bonding, [28][29][30][31] chargetransfer, [32][33][34][35][36][37] and halogen bonding interactions, [38,39] while alloys are constructed by substitution of structurally matched guest molecules at the host sites. [40][41][42][43][44][45] While binary heterostructures capable of producing well-defined micro-and nanoscale interfaces can be viewed as partially compatible combinations.…”

Selective Extraction, Recovery, and Sensing of Hydroquinone Mediated by a Supramolecular Pillar[5]quinone Quinhydrone Charge-Transfer Complex

“…Imaging of the P [5]Q-HQ nanostructure by the scanning electron microscopy (SEM) technique demonstrated the formation of microcrystalline particles (40−50 μm) in contrast to the needle-shape microcrystals of the parent P [5]Q structure which possesses a size range of 1−5 μm (Figure 5b). Furthermore, nitrogen adsorption experiments carried out on P [5]Q and the P[5]Q-HQ complex, measured in different sorption methods (Figure S15 and Table S3), elucidated that the BET surface areas are small, 18 m 2 /g and 6 m 2 /g, respectively, but distinct from each other, 26,45 which is rationalized by the nonporous structures of pillararene derivatives. 46 Attention was subsequently directed toward characterizing the electrochemical properties of the complex.…”

“…Courtesy of recent synthetic advances in pillar[5]­arene chemistry, the electron-donating properties of the dialkyl hydroquinone aromatic panels can be reversed by oxidation to pillar[5]­quinone (P[5]­Q). − However, the poor solubility of P[5]­Q in common organic solvents and water has restricted its uses in only a handful of applications such as nanocomposite materials in lithium and sodium-ion batteries. − It has been shown that intermolecular charge transfer interactions between benzoquinone (BQ) units of P[5]­Q and benzene-1,4-diol panels of deprotected pillararene derivatives give rise to the formation of a quinhydrone-type complex and notably demonstrate considerable electronic communication between quinone units. − Such interactions have been employed in the fabrication of nanostructures including vesicles, fibers, and porous carbon materials; however the application of P[5]­Q for purposes of hydroquinone recognition and isomer separation is unprecedented. − Motivated by these observations, we sought to exploit P[5]­Q for the purposes of a supramolecular-based strategy to selectively recognize, sense, and extract hydroquinone (HQ) over closely related catechol (CC) and resorcinol (RS) regioisomers.…”