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Host–Guest Molecular Crystals of Diamino-4,4-bithiazole and Dynamic Molecular Motions via Guest Sorption

2017; American Chemical Society; Volume: 18; Issue: 1 Linguagem: Inglês

10.1021/acs.cgd.7b01236

1528-7505

Hiroshi Nishiyama, Takashi Takeda, Norihisa Hoshino, Kiyonori Takahashi, Shin‐ichiro Noro, Takayoshi Nakamura, Tomoyuki Akutagawa,

Luminescence and Fluorescent Materials

Diamino-4,4-bithiazole (1) formed host–guest binary molecular crystals with various types of organic guest molecules including pyridine (Py), benzonitrile (PhCN), piperidine (Pipe), DMF, THF, 1,4-dioxane (Diox), CH3OH, aniline (Ani), coumarin (Coum), nitrobenzene (PhNO2), hexamethylenetetramine (HMTA), and quinoline (Quino). Single crystal X-ray structural analyses at 100 K revealed the formation of 1·(guest) or 1·(guest)2 crystals. Reversible molecular adsorption–desorption responses were observed with Py, PhCN, Pipe, DMF, and Diox around room temperature as the crystalline powders were heated during the desorption process and exposed to guest vapor during the readsorption process. The adsorption–desorption isotherms of crystalline powders 1 with Diox at 298 K indicated a reversible gate-opening adsorption–desorption process. Although the host–guest molecular crystals 1·(THF)2 and 1·(CH3OH)2 were confirmed by X-ray crystal structural analyses at 100 K, the THF and CH3OH guests were already eliminated at room temperature. Guest desorption processes of crystalline powders 1·(guest)x were not observed in the host–guest molecular crystals with Ani, Coum, PhNO2, HMTA, and Quino after the crystalline powders were heated. A balance of both the dipole moment and vapor pressure of the guest molecules played an essential role to elicit reversible guest sorption. The crystal structures formed on account of double N–H···N hydrogen-bonded one-dimensional (1D) chains between the −NH2 group and the ring nitrogen atom of 1, which interacted to form two-dimensional (2D) sheet structures through π-stacking and/or S···S interactions. Alternating layers of N–H···N hydrogen-bonded herringbone packing of 1 and the guest molecules led to the formation of other types of crystal lattices. The hydrogen-bonding molecular assemblies of 1 demonstrated lattice flexibly via the configuration change in the molecular arrangements according to the boiling point of the guest molecules.