21004-11-5Relevant articles and documents
Fine-tuning the pore structure of metal-organic frameworks by linker substitution for enhanced hydrogen storage and gas separation
Han, Xiwei,Yang, Xiaoxian,Yu, Chuan,Lu, Shuyan,Pouya, Ehsan Sadeghi,Bai, Peng,Lyu, Jiafei,Guo, Xianghai
, p. 3026 - 3032 (2021/05/03)
The modification of metal-organic frameworks (MOFs) by functionalizing ligands has been investigated for improved properties. In this study, by introducing substituents to the backbone of organic linkers, isostructural dihydroxy-/dialkoxy-functionalized Zr-MOFs were delicately constructed and sophisticatedly characterized for crystallinity, morphology, porosity and structural defects. Pure-component CO2, CH4, N2, and H2adsorption isotherms on the microporous synthesized materials were investigated under the pressure up to 10 MPa at 303 K. By the ideal adsorbed solution theory (IAST) model, enhanced adsorption selectivity towards CO2/N2, CO2/CH4, CH4/N2and CO2/H2binary mixtures was observed compared to the parent material, and dihydroxy functionalization endows the material with high selectivity towards CO2/H2. Moreover, the diethoxy-functionalized material with narrow cavities exhibits improved high pressure H2adsorption due to structural defects and strong overlapping potentials.
A Covalent and Modular Synthesis of Homo- And Hetero[ n]rotaxanes
Cornelissen, Milo D.,Fr?lke, Steven,J?rgensen, Steen Ingemann,Pilon, Simone,Steemers, Luuk,Van Der Vlugt, Jarl Ivar,Van Maarseveen, Jan H.,Wanner, Martin J.,Zuidinga, Ed
, p. 3146 - 3159 (2020/03/23)
Incorporation of 2,5-dihydroxyterephthalate as a covalent scaffold in the axis of a 30-membered all-carbon macrocycle provides access to a modular series of rotaxanes. Installment of tethered alkynes or azides onto the terephthalic phenolic hydroxyl functionalities, which are situated at opposite sides of the macrocycle, gives versatile prerotaxane building blocks. The corresponding [2]rotaxanes are obtained by introduction of bulky stoppering ("capping") units at the tethers and subsequent cleavage of the covalent ring/thread ester linkages. Extension of this strategy via coupling of two prerotaxanes bearing complementary linker functionalities (i.e., azide and alkyne) and follow-up attachment of stopper groups provide efficient access to [n]rotaxanes. The applicability and modular nature of this novel approach were demonstrated by the synthesis of a series of [2]-, [3]-, and [4]rotaxanes. Furthermore, it is shown that the prerotaxanes allow late-stage functionalization of the ring fragment introducing further structural diversity.
(Poly)terephthalates with Efficient Blue Emission in the Solid State
Shimizu, Masaki,Shigitani, Ryosuke,Kinoshita, Takumi,Sakaguchi, Hiroshi
, p. 1792 - 1800 (2019/01/08)
We prepared dimethyl and diaryl 2,5-dialkoxytere-phthalates from dimethyl 2,5-dihydroxyterephthalate in good-to-high yields via alkylation or a sequence of alkylation, hydrolysis, chlorination, and condensation. The absorption spectra of the dialkoxyterephthalates contain a small band at 332–355 nm, which could be assigned to intramolecular charge-transfer transition from the alkoxy to alkoxycarbonyl groups on the basis of theoretical calculations using density functional theory. The dialkoxyterephthalates exhibited blue fluorescence with moderate-to-excellent quantum yields not only in solution but also in the solid state, such as a poly(methyl methacrylate) (PMMA) film and a powder. The solid-state quantum yields of the diisopropoxy-substituted terephthalates were similar or considerably higher than those of the dimethoxy-substituted counterparts. Copolymerization of 2,5-diisopropoxyterephthaloyl chloride and 1,4-butanediol with or without terephthaloyl chloride gave brilliantly blue fluorescent polymers, whose quantum yields were 0.72 and 0.71 in toluene and 0.46 and 0.40 in the neat film, respectively. Furthermore, white emission was achieved when a fluorescent yellow 2,5-diaminoterephthalate was doped into the thin film of the blue fluorescent polymer at 0.4 wt %.
