1. Porous Organic Salts: Diversifying Void Structures and Environments
Takahiro Ami, Kouki Oka, Keiho Tsuchiya, Norimitsu Tohnai Angew Chem Int Ed Engl. 2022 Aug 1;61(31):e202202597. doi: 10.1002/anie.202202597. Epub 2022 May 19.
Porous organic salts (POSs) are porous organic materials, in which various aromatic sulfonic acids and amines are regularly self-assembled by charge-assisted hydrogen bonding. POSs exhibit high solubility in highly polar solvents. Therefore, they are prepared via facile recrystallization and exhibit high recyclability. In this study, tetrahedral-structured tetrasulfonic acid and triphenylmethylamine (TPMA) were combined to construct POSs with rigid diamond networks called diamondoid porous organic salts (d-POSs). Furthermore, by introducing substituents (e.g., F, Cl, Br, or I) at the para-positions of benzene rings of TPMA, these substituents were exposed on the void surface of d-POSs, and their diamond networks were distorted. This induced the formation of a variety of void structures and environments in the d-POSs, which significantly affected their gas adsorption behavior. In particular, the d-POS from TPMA substituted by fluorine exhibited very high CO2 adsorption of 182 mL(STP) g-1 at 1 atm in all-organic porous materials.
2. Photoinduced electron transfer in porous organic salt crystals impregnated with fullerenes
Tetsuya Hasegawa, Kei Ohkubo, Ichiro Hisaki, Mikiji Miyata, Norimitsu Tohnai, Shunichi Fukuzumi Chem Commun (Camb). 2016 Jun 28;52(51):7928-31. doi: 10.1039/c6cc02377k. Epub 2016 May 16.
Porous organic salt (POS) crystals composed of 9-(4-sulfophenyl)anthracene (SPA) and triphenylmethylamine (TPMA) were impregnated with fullerenes (C60 and C70), which were arranged in one dimensional close contact. POS crystals of SPA and TPMA without fullerenes exhibit blue fluorescence due to SPA, whereas the fluorescence was quenched in POS with fullerenes due to electron transfer from the singlet excited state of SPA to fullerenes.
3. A new polymorph of triphenylmethylamine: the effect of hydrogen bonding
Victor N Khrustalev, Irina V Borisova, Nikolai N Zemlyansky, M Yu Antipin Acta Crystallogr C. 2009 Feb;65(Pt 2):o31-4. doi: 10.1107/S0108270108042911. Epub 2009 Jan 10.
Crystallization of the hexane reaction mixture after treatment of LiGe(OCH(2)CH(2)NMe(2))(3) with Ph(3)CN(3) gives rise to a new triclinic (space group P\overline{1}) polymorph of triphenylmethylamine, C(19)H(17)N, (I), containing dimers formed by N-H...N hydrogen bonds, whereas the structure of the known orthorhombic (space group P2(1)2(1)2(1)) polymorph of this compound, (II), consists of isolated molecules. While the dimers in (I) lie across crystallographic inversion centres, the molecules are not truly related by them. The centrosymmetric structure is due to the statistical disordering of the amino H atoms participating in the N-H...N hydrogen-bonding interactions, and thus the inversion centre is superpositional. The conformations and geometric parameters of the molecules in (I) and (II) are very similar. It was found that the polarity of the solvent does not affect the capability of triphenylmethylamine to crystallize in the different polymorphic modifications. The orthorhombic polymorph, (II), is more thermodynamically stable under normal conditions than the triclinic polymorph, (I). The experimental data indicate the absence of a phase transition in the temperature interval 120-293 K. The densities of (I) (1.235 Mg m(-3)) and (II) (1.231 Mg m(-3)) at 120 K are practically equal. It would seem that either the kinetic factors or the effects of the other products of the reaction facilitating the hydrogen-bonded dimerization of triphenylmethylamine molecules are the determining factor for the isolation of the triclinic polymorph (I) of triphenylmethylamine.