Many of alkylureas (H 2 NCONHC n H 2n+1 , C n -U) exhibited phase transitions and those found for C 4, 8 -U had fairly large entropy of transition, indicating formation of quasiplastic phases. X-ray structure determinations of C 2, 5-14 -U revealed a characteristic common hydrogen bond network to result in the formation of two-dimensional, platelike supramolecules having crossed arrangement of alkyl groups. The crystal structures of C 2, 5-14 -U were found to be built by stacking the corresponding supramolecules along the a axis. The phase transitions of C 10, 13, 14 -U and those of C 8, 12 -U were found to accompany shifts of supramolecules along the crystal c axis and along both the b and c axes respectively. The transitions found for C 4 , 8 -U were proved to be of order-disorder type associated with the disordering of the alkyl groups. The transition of C 4 -U was found to be associated with a drastic twist of the plane of the NCON moiety. The transition temperatures of C 4 -U and C 8 -U were depressed significantly by doping C 3 -U

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タイトル TitleSolid solution of triptycenequinone and triptycenehydroquinone as a non-stoichiometric quinhydrone. Bathochromic changes in color caused by local intermolecular interaction between p-benzoquinone and hydroquinone moieties Abstract Binary crystal formed by 9,10-dihydro-9,10-[o]benzenoanthracene-1,4-dione (triptycenequinone, TPQ, yellow) and 9,10-dihydro-9,10-[o]benzenoanthracene-1,4-diol (triptycenehydroquinone, TPHQ, colorless) was found to be a substitutional solid solution of TPQ doped by TPHQ with concentration of TPHQ < ca.0.2. The characteristic color (brown) of the solid solution may be ascribed to local intermolecular CT interaction between the p-benzoquinone and hydroquinone moieties of TPQ and TPHQ, respectively, enabled by a disorder in the binary crystal. It seemed appropriate to regard the solid solution as non-stoichiometric quinhydrone. Crystal structure of pure TPHQ is also reported. A common molecular arrangement in the crystals of pure TPQ and pure TPHQ, as well as the resemblance in the molecular structure, seems to be favorable for the formation of the solid solution.

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1,4-Dimethoxytriptycene (diMeO-TP) and triptycenequinone (TPQ), non-planar donor and acceptor molecules respectively, were found to form two types of mixed crystals with limited solubility, i.e., (diMeO-TP) x (TPQ) 1-x with x=ca.0.25 and (diMeO-TP) x (TPQ) 1-x with x=ca.0.97. Crystal structures of the mixed crystals suggested that their characteristic colors, which are different from those of TPQ (yellow) and diMeO-TP (colorless), are caused by local CT interactions between 1,4-benzoquinone and 1,4-dimethoxybenzene moieties in the crystals. The present mixed crystals can be regarded as non-stoichiometric quinhydrone-type CT complexes similar to that formed by TPQ and TPHQ (triptycenehydroquinone).