3805-38-7Relevant academic research and scientific papers
An Extra-Large-Pore Pure Silica Zeolite with 16×8×8-Membered Ring Pore Channels Synthesized using an Aromatic Organic Directing Agent
Cai, Xian-Shu,Chen, Fei-Jian,Du, Hong-Bin,Gao, Zihao,Zhang, Jun,Zhao, Bao-Xun,Zi, Wen-Wen
, p. 3948 - 3951 (2020)
Extra-large-pore zeolites for processing large molecules have long been sought after by both the academia and industry. However, the synthesis of these materials, particularly extra-large-pore pure silica zeolites, remains a big challenge. Herein we report the synthesis of a new extra-large-pore silica zeolite, designated NUD-6, by using an easily synthesized aromatic organic cation as structure-directing agent. NUD-6 possesses an intersecting 16×8×8-membered ring pore channel system constructed by four-connected (Q4) and unusual three-connected (Q3) silicon species. The organic cations in NUD-6 can be removed in nitric acid to yield a porous material with high surface area and pore volume. The synthesis of NUD-6 presents a feasible means to prepare extra-large pore silica zeolites by using assembled aromatic organic cations as structure-directing agents.
The regioselectivity and synthetic mechanism of 1,2-benzimidazole squaraines: Combined experimental and theoretical studies
Xia, Guomin,Wu, Zhiwei,Yuan, Yanli,Wang, Hongming
, p. 18055 - 18061 (2013)
In this paper, a synthetic method to produce 1,2-benzimidazole squaraines with a yield of up to 89% is developed. It is found that both strong organic and inorganic bases have a satisfactory catalytic activity for this reaction. Theoretical studies provide detailed explanations for the 1,2 versus 1,3 condensation regiochemistry of the squaraines. The experimental and theoretical studies agree well with each other, paving a practical way to efficiently synthesize 1,2-squaraines. The Royal Society of Chemistry.
Mesoporous silica nanobeans dual-functionalized with AIEgens and leaning pillar[6]arene-based supramolecular switches for imaging and stimuli-responsive drug release
Li, Xiangshuai,Han, Junyou,Qin, Jianchun,Sun, Ming,Wu, Jiarui,Lei, Liancheng,Li, Jing,Fang, Lei,Yang, Ying-Wei
, p. 14099 - 14102 (2019)
A bean-shaped and dual-functionalized organic-inorganic hybrid supramolecular system with a GSH-dependent turn-on fluorescence enhancement property and stimuli-responsive drug delivery function endowed with leaning towerarene-based switches has been const
Br?nsted Basicities and Nucleophilicities of N-Heterocyclic Olefins in Solution: N-Heterocyclic Carbene versus N-Heterocyclic Olefin. Which Is More Basic, and Which Is More Nucleophilic?
Li, Zhen,Ji, Pengju,Cheng, Jin-Pei
, p. 2974 - 2985 (2021/02/06)
A Br?nsted basicity scale comprising nine representative N-heterocyclic olefins (NHOs) was established by measuring the equilibrium acidities of their corresponding precursors in DMSO using an ultraviolet-visible spectroscopic method. The basicities (pKaHs) of the investigated NHOs cover a range from 14.7 to 24.1. The basicities of unsaturated NHOs are stronger than those of their N-heterocyclic carbene (NHC) analogues; however, the basicities for the saturated ones are much weaker than those of their NHC analogues, which is largely due to the aromatization effect that intrinsically influences the acidic dissociations of NHC and NHO precursors. The nucleophilicities of four NHOs were measured photometrically by monitoring the kinetics of reactions of these NHOs with common reference electrophiles for quantifying nucleophilic reactivities. In general, the nucleophilicity of the NHOs is much stronger than that of commonly used Lewis bases such as Ph3P or DMAP [4-(dimethylamino)pyridine] but weaker than that of their NHC analogues; however, caution should be taken when generalizing this conclusion to a wide range of electrophiles with distinctively electronic and structural properties.
Addressing Reversibility of R-NHC Coupling on Palladium: Is Nano-to-Molecular Transition Possible for the Pd/NHC System?
Denisova, Ekaterina A.,Eremin, Dmitry B.,Gordeev, Evgeniy G.,Tsedilin, Andrey M.,Ananikov, Valentine P.
, p. 12218 - 12227 (2019/09/30)
It has recently been shown that palladium-catalyzed reactions with N-heterocyclic carbene (NHC) ligands involve R-NHC coupling accompanied by transformation of the molecular catalytic system into the nanoscale catalytic system. An important question appeared in this regard is whether such a change in the catalytic system is irreversible. More specifically, is the reverse nano-to-molecular transformation possible? In view of the paramount significance of this question to the area of catalyst design, we studied the capability of 2-substituted azolium salts to undergo the breakage of C-C bond and exchange substituents on the carbene carbon with corresponding aryl halides in the presence of Pd nanoparticles. The study provides important experimental evidence of possibility of the reversible R-NHC coupling. The observed behavior indicates that the nanosized metal species are capable of reverse transition to molecular species. Such an option, known for phosphine ligands, was previously unexplored for NHC ligands. The present study for the first time demonstrates bidirectional dynamic transitions between the molecular and nanostructured states in Pd/NHC systems. As a unique feature, surprisingly small activation barriers (18 kcal/mol) and noticeable thermodynamic driving force (-5 to -7 kcal/mol) were calculated for C-C bond oxidative addition to Pd(0) centers in the studied system. The first example of NHC-mediated Pd leaching from metal nanoparticles to solution was observed and formation of Pd/NHC complex in solution was detected by ESI-MS.
Benzimidazoles as Metal-Free and Recyclable Hydrides for CO2 Reduction to Formate
Lim, Chern-Hooi,Ilic, Stefan,Alherz, Abdulaziz,Worrell, Brady T.,Bacon, Samuel S.,Hynes, James T.,Glusac, Ksenija D.,Musgrave, Charles B.
, p. 272 - 280 (2019/01/04)
We report a novel metal-free chemical reduction of CO2 by a recyclable benzimidazole-based organo-hydride, whose choice was guided by quantum chemical calculations. Notably, benzimidazole-based hydride donors rival the hydride-donating abilities of noble-metal-based hydrides such as [Ru(tpy)(bpy)H]+ and [Pt(depe)2H]+. Chemical CO2 reduction to the formate anion (HCOO-) was carried out in the absence of biological enzymes, a sacrificial Lewis acid, or a base to activate the substrate or reductant. 13CO2 experiments confirmed the formation of H13COO- by CO2 reduction with the formate product characterized by 1H NMR and 13C NMR spectroscopy and ESI-MS. The highest formate yield of 66% was obtained in the presence of potassium tetrafluoroborate under mild conditions. The likely role of exogenous salt additives in this reaction is to stabilize and shift the equilibrium toward the ionic products. After CO2 reduction, the benzimidazole-based hydride donor was quantitatively oxidized to its aromatic benzimidazolium cation, establishing its recyclability. In addition, we electrochemically reduced the benzimidazolium cation to its organo-hydride form in quantitative yield, demonstrating its potential for electrocatalytic CO2 reduction. These results serve as a proof of concept for the electrocatalytic reduction of CO2 by sustainable, recyclable, and metal-free organo-hydrides.
A small-molecule with a large two-photon absorption cross-section serves as a membrane-permeable ribonucleic acid (RNA) probe for live cell imaging
Feng, Ruiqing,Li, Longlong,Li, Bing,Li, Jinhui,Peng, Dan,Yu, Yitao,Mu, Qiuhong,Zhao, Ning,Yu, Xiaoqiang,Wang, Zhenhua
supporting information, p. 14325 - 14331 (2018/08/28)
We have synthesized a two-photon organic small-molecule probe (DMI), which has a considerable two-photon absorption cross section (δ) value and selectively stained endogenous RNA in the nucleolus and the cytoplasm of living cells with outstanding membrane
Two-photon fluorescence probe for RNA imaging and application thereof in living cells
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Paragraph 0028; 0029, (2017/08/28)
The invention relates to a two-photon fluorescence probe for RNA imaging and an application thereof in living cells. A structural general formula of the probe is shown as (I), wherein R is hydrogen, alkyl group, hydroxyalkyl or ether group, and X is bromi
Expanding the Ligand Framework Diversity of Carbodicarbenes and Direct Detection of Boron Activation in the Methylation of Amines with CO2
Chen, Wen-Ching,Shen, Jiun-Shian,Jurca, Titel,Peng, Chun-Jung,Lin, Yen-Hsu,Wang, Yi-Ping,Shih, Wei-Chih,Yap, Glenn P. A.,Ong, Tiow-Gan
supporting information, p. 15207 - 15212 (2016/01/25)
A simple and convergent synthetic strategy used to increase the diversity of the carbodicarbene ligand framework through incorporation of unsymmetrical pendant groups is reported. Structural analysis and spectroscopic studies of ligands and their Rh complexes are reported. Reactivity studies reveal carbodicarbenes as competent organocatalysts for amine methylation using CO2 as a synthon. A unique B-H-activated boron-carbodicarbene complex was isolated as a reaction intermediate, providing mechanistic insight into the CO2 functionalization process.
Synthesis, spectral properties of cell-permeant dimethine cyanine dyes and their application as fluorescent probes in living cell imaging and flow cytometry
Zhang,Liu,Shi,Wang,Fu,Wei,Yang
, p. 232 - 240 (2013/10/22)
A series of dimethine cyanine dyes, used as fluorescent probes, were synthesized under microwave irradiation, and identified by 1H NMR, IR, elemental analysis and HRMS. The investigation of their spectral properties in phosphate-buffer saline (PBS) showed that the absorption and emission maxima of the dyes were in the region 370-480 nm and 471-569 nm, respectively. The properties of the dyes as fluorescent probes for living cells imaging and flow cytometry were investigated. The results showed that dyes 1, 2, 8 or 9 could penetrate an intact cell membrane, stained the cell nuclear and exhibited bright fluorescence. Little background interference, low cell cytotoxicity and little photobleaching were showed during the imaging tests. The dyes 1, 8 and 9 could be applied in flow cytometry and dye 1/PI, dye 8/PI or dye 9/PI couple could be proposed as double staining agents to measure sperm cell viability. Thus the dyes represented the cell-permeant fluorescent probes.
