A dielectric constant transition is chemically triggered and thermally switched in (HPy)2[Na(H2O)Co(CN)6] ( 2 , HPy=pyridinium cation) by single‐crystal‐to‐single‐crystal transformation and structural phase transition, respectively. Upon dehydration, (HPy)2[Na(H2O)2Co(CN)6] ( 1 ) transforms to its semi‐hydrated form 2 , accompanying a transition from a low‐dielectric state to a high‐dielectric state, and vice versa. This dielectric switch is also realized by a structural phase transition in 2 that occurs between room‐ and low‐temperature phases, and which corresponds to high‐ and low‐dielectric states, respectively. The switching property is due to the variation in the environment surrounding the HPy cation, that is, the hydrogen‐bonding interactions and the crystal packing, which exert predominant influences on the dynamics of the cations that transit between the static and motional states. 相似文献
The controlled generation of singlet oxygen is of great interest owing to its potential applications including industrial wastewater treatment, photochemistry, and photodynamic therapy. Two photochromic metal–organic frameworks, PC‐PCN and SO‐PCN, have been developed. A photochromic reaction has been successfully realized in PC‐PCN while maintaining its single crystallinity. In particular, as a solid‐state material which inherently integrates the photochromic switch and photosensitizer, SO‐PCN has demonstrated reversible control of 1O2 generation. Additionally, SO‐PCN shows catalytic activity towards photooxidation of 1,5‐dihydroxynaphthalene. 相似文献
We describe an anodic stripping voltammetric (ASV) method for glucose sensing that widely expands the typical amperometric i-t response of glucose sensors. The electrode is based on a working electrode consisting of a glassy carbon electrode modified with Pt-Pd nanoparticles (NPs; in an atomic ratio of 3:1) on a reduced graphene oxide (rGO) support. The material was prepared via the spontaneous redox reaction between rGO, PdCl42− and PtCl42− without any additional reductant or surfactant. Unlike known Pt-based sensors, the use of Pt3Pd NPs results in an ultrasensitive ASV approach for sensing glucose even at near-neutral pH values. If operated at a working voltage as low as 0.06 V (vs. SCE), the modified electrode can detect glucose in the 2 nM to 300 μM concentration range. The lowest detectable concentration is 2 nM which is much lower than the LODs obtained with other amperometric i-t type sensing approaches, most of which have LODs at a μM level. The sensor is not interfered by the presence of 0.1 M of NaCl.
Two uranyl complexes based on pyromellitic acid were hydrothermally synthesized, and their X‐ray single‐crystal diffraction structures were determined. Complex [UO2(Hbtec)]–(Himd)+ · H2O ( 1 ) (H4btec = pyromellitic acid, imd = imidazole), is an ionic complex, which shows a typical (4, 4) topological structure in the space. A heterometallic complex, UO2Cu(btec)(phen) ( 2 ) (phen = 1,10‐phenanthroline) results from the reaction of uranyl nitrate and copper(II) bromide with pyromellitic acid. The structure of complex 2 revealed that the chains of UO7 and CuO3N2 units were connected to each other through the carboxyl groups and U=O–Cu interactions to create a two‐dimensional framework. 相似文献
For forensic and population genetic purposes, a total of 125 unrelated volunteers’ blood samples were collected from Chinese Bai ethnic minority group to analyze sequence variation of two hypervariable segments (HVS‐I and HVS‐II) in the mitochondrial DNA control region. Comparing the HVS‐I and HVS‐II sequences of the 125 Chinese Bais to the Anderson reference sequence, we found 86 polymorphic loci in HVS‐I and 40 in HVS‐II in mitochondrial DNA sequences of the Chinese Bai ethnic minority group, which defined 93 and 53 different haplotypes, respectively. Haplotype diversity and the mean pairwise differences were 0.992 ± 0.003 and 6.553 in HVS‐I, and 0.877 ± 0.027 and 2.407 in HVS‐II, respectively. We defined four macrohaplogroups R, M, N and D with the proportions ranging from 9.6% to 40.0%. With the analysis of the hypervariable domain from nucleotide 16 180–16 193 in HVS‐I, our study revealed new haplotypes of sequence variations. In addition, the Fst metric, phylogenetic tree, and principal component analysis demonstrated a close genetic relationship between the Bai group and Chinese Han populations from South China, Changsha, and Guangdong. The results support that the Bai group is a multiorigin ethnic minority that has merged with the Chinese Han population. 相似文献
One new lactone, cyclopentanepyrone A ( 1 ), and two new monoterpenoids, gardeterpenone A ( 2 ) and jasminoside V ( 3 ), were isolated from the fruits of Gardenia jasminoides var. radicans, along with four known monoterpenoids, 4 – 7 , which were isolated from this plant for the first time. The structures of the isolates were elucidated by extensive spectroscopic studies, including UV, IR, 1D‐ and 2D‐NMR, ESI‐MS, HR‐ESI‐MS, and CD experiments. 相似文献