13962-92-0Relevant articles and documents
Planarity of terphenyl rings possessing: O -carborane cages: Turning on intramolecular-charge-transfer-based emission
So, Hyunhee,Kim, Jea Ho,Lee, Ji Hye,Hwang, Hyonseok,An, Duk Keun,Lee, Kang Mun
, p. 14518 - 14521 (2019)
To clarify the relationship between planarity and intramolecular charge transfer (ICT), two o-carboranyl compounds (TCB and FCB) containing different ortho-type terphenyl rings, namely, perfectly distorted or planar phenyl rings, were synthesised and fully characterised. Although the emission spectra of both compounds presented intriguing dual-emission patterns in solution at 298 or 77 K and in the film state, distorted TCB mostly showed locally excited emission, whereas planar FCB demonstrated intense emission corresponding to an ICT transition. Interestingly, the emission efficiencies and radiative decay constants of terphenyl-based o-carboranyl compounds were gradually enhanced by increasing the planarity of the terphenyl groups. These results verify the existence of a strong relationship between the planarity of appended aryl groups and ICT-based radiative decay in o-carborane-substituted compounds.
Activation-Dependent Breathing in a Flexible Metal–Organic Framework and the Effects of Repeated Sorption/Desorption Cycling
Engel, Emile R.,Jouaiti, Abdelaziz,Bezuidenhout, Charl X.,Hosseini, Mir Wais,Barbour, Leonard J.
, p. 8874 - 8878 (2017)
A non-interpenetrated metal–organic framework with a paddle-wheel secondary building unit has been activated by direct thermal evacuation, guest exchange with a volatile solvent, and supercritical CO2 drying. Conventional thermal activation yields a mixture of crystalline phases and some amorphous content. Exchange with a volatile solvent prior to vacuum activation produces a pure breathing phase with high sorption capacity, selectivity for CO2 over N2 and CH4, and substantial hysteresis. Supercritical drying can be used to access a guest-free open phase. Pressure-resolved differential scanning calorimetry was used to confirm and investigate a systematic loss of sorption capacity by the breathing phase as a function of successive cycles of sorption and desorption. A corresponding loss of sample integrity was not detectable by powder X-ray diffraction analysis. This may be an important factor to consider in cases where flexible MOFs are earmarked for industrial applications.
Molecular packing and morphological stability of dihydro-indeno[1,2-: B] fluorenes in the context of their substitution pattern
Hempe,Reggelin
, p. 47183 - 47189 (2017/10/19)
The synthesis of a series of dihydroindeno[1,2-b]fluorene (IF) derivatives with various side chain substituents is reported, these have been investigated by single-crystal X-ray analysis in terms of their molecular packings and the thermal stability of these morphologies observed by DSC measurements. It is shown that symmetrically substituted IFs bearing longer linear aliphatic side chains tend to crystallize in thermolabile coplanar layers, in which the aliphatic and dihydroindeno[1,2-b]fluorene core segments are spatially segregated. In contrast to that, the attachment of aryl side chains to the dihydroindenofluorene core results in a stabilization of the cofacial morphology, which can be observed by the absence of thermal phase transitions. In addition to this, asymmetrically substituted derivatives, so called "mixed indenofluorenes" (MIFs), bearing pairwise linear aliphatic side chains of variable length, as well as aryl substituents have been synthesized. These derivatives tend to exhibit thermostable morphologies with an enhanced tendency to form edge-to-face contacts of the dihydroindenofluorene structures.
