6962-04-5Relevant articles and documents
Emission-Tunable Soft Porous Organic Crystal Based on Squaraine for Single-Crystal Analysis of Guest-Induced Gate-Opening Transformation
Li, Lin,Ma, Huili,Zhang, Jingyan,Zhao, Engui,Hao, Jian,Huang, Huiming,Li, Hui,Li, Pengfei,Gu, Xinggui,Tang, Ben Zhong
, p. 3856 - 3864 (2021)
Soft porous crystals (SPCs) with both crystallinity and flexibility have evolved as emerging materials for lots of applications. However, the development of purely organic SPCs (SPOCs) with advanced functionalities significantly lags behind. Herein, we report the construction of an emission-tunable SPOC with a rationally designed squaraine derivative (named as SPOC-SQ). SPOC-SQ is featured with a squaraine core and four peripheries with electron donor-π-acceptor (D-π-A) characteristics, which facilitates the formation of porous crystal framework stabilized by π-πinteractions and H bonds and at the same time provides structural flexibility through phenyl rotations. This SPOC can be easily obtained from its dichloromethane (DCM) solution and exhibits reversible stimuli-responsive single-crystal-to-single-crystal (SCSC) structural transformation, accompanied by bright and tunable emission. In addition, this activated SPOC (SPOC-SQ-a) selectively recognizes and absorbs acetylene (C2H2) over other gases without destroying the single crystallinity, enabling the single-crystal XRD analysis of the structural transformation. Close inspection of single-crystal XRD results of SPOC-SQ-C2H2 facilitates the understanding of the host-guest interactions. More interestingly, upon interacting with C2H2, a one-dimensional (1D) channel is formed in the crystal to adopt C2H2, which proves the SCSC process and provides molecular-level insights into the gate-opening process. Furthermore, C2H2 adsorption dynamics can be monitored in real time by tracking the fluorescence wavelength changes of SPOC-SQ framework. Thus, the unique gate-opening sorption attribute of SPOC-SQ-a crystals toward C2H2 enables its potential applications for gas separation.
High-Throughput Mass Spectrometry Screening Platform for Discovering New Chemical Reactions under Uncatalyzed, Solvent-Free Experimental Conditions
Kulyk, Dmytro S.,Amoah, Enoch,Badu-Tawiah, Abraham K.
, p. 15025 - 15033 (2020/12/01)
A gas-phase high-throughput reaction screening platform was developed for the first time to study chemical structures of closely related functional groups and for the discovery of novel organic reaction pathways. Experiments were performed using the contained atmospheric pressure chemical ionization (APCI) source that enabled nonthermal, nonequilibrium plasma chemistry to be monitored by mass spectrometry (MS) in real time. This contained-APCI MS platform allowed an array of reagents to be tested, resulting in the studies of multiple gas-phase reactions in parallel. By exposing headspace vapor of the selected reagents to corona discharge, solvent-free Borsche-Drecsel cyclization reaction, Katritzky chemistry, and Paal-Knorr pyrrole synthesis were examined in the gas phase, outside the high vacuum environment of the mass spectrometer. A new radical-mediated hydrazine coupling reaction was also discovered, which provided a selective pathway to synthesize secondary amines without using a catalyst. The mechanisms of these atmospheric pressure gas-phase reactions were explored through the direct capture of intermediates and via comparison with the corresponding bulk solution and droplet-phase reactions.
Copper complexes of 1,4-diazabutadiene ligands: Tuning of metal oxidation state and, application in catalytic C-C and C-N bond formation
Mukherjee, Aparajita,Basu, Semanti,Bhattacharya, Samaresh
, (2019/11/11)
Reaction of 1,4-diazabutadiene (p-RC6H4N = C(H)(H)C = NC6H4R-p; R = OCH3, CH3, H and Cl; abbreviated as L-R) with CuCl2·2H2O in methanol at ambient temperature (25 °C) affords a group of doubly chloro-bridged dicopper complexes of type [{CuI(L-R)Cl}2], designated as 1-R. Similar reaction carried out in acetonitrile furnishes a family of doubly chloro-bridged dicopper complexes of type [{CuII(L-R)Cl2}2], designated as 2-R. Molecular structures of 1-OCH3 and 2-OCH3 have been determined by X-ray crystallography. While copper(I) is having a nearly tetrahedral N2Cl2 coordination sphere in 1-OCH3, the N2Cl3 coordination sphere around copper(II) is distorted square pyramidal in nature in 2-OCH3. Isolated 2-R complexes, on dissolution in methanol, are found to undergo facile reduction of the metal center to generate the corresponding 1-R complexes. The 1-R and 2-R complexes show intense absorptions in the visible and ultraviolet regions. Cyclic voltammetry on the 1-R and 2-R complexes shows both metal-centered and ligand centered redox responses. The 1-R complexes are found to efficiently catalyze C-N cross-coupling reactions between arylboronic acids and aryl amines; while the 2-R complexes display notable catalytic efficiency for nitroaldol reactions.
Fundamentally Different Distance Dependences of Electron-Transfer Rates for Low and High Driving Forces
Neumann, Svenja,Wenger, Oliver S.
supporting information, p. 855 - 860 (2019/01/11)
The distance dependences of electron-transfer rates (kET) in three homologous series of donor-bridge-acceptor compounds with reaction free energies (ΔGET0) of ca. -1.2, -1.6, and -2.0 eV for thermal charge recombination after initial photoinduced charge separation were studied by transient absorption spectroscopy. In the series with low driving force, the distance dependence is normal and kET decreases upon donor-acceptor distance (rDA) elongation. In the two series with higher driving forces, kET increases with increasing distance over a certain range. This counterintuitive behavior can be explained by a weakly distance-dependent electronic donor-acceptor coupling (HDA) in combination with an increasing reorganization energy (λ). Our study shows that highly exergonic electron transfers can have distance dependences that differ drastically from those of the more commonly investigated weakly exergonic reactions.
Tuning the Photophysical Properties of Symmetric Squarylium Dyes: Investigation on the Halogen Modulation Effects
Chen, Weiben,Zhang, Simeng,Dai, Gaole,Chen, Ying,Li, Miao,Zhao, Xiaoyu,Chen, Yulan,Chen, Long
supporting information, p. 469 - 473 (2019/01/04)
A series of symmetric squarylium dyes (SQDPA-X) with different halogen (X=F, Cl, Br, I) substituents have been developed. The photophysical properties could be facilely tuned by the halogen modulation effects. The strategy of incorporating different halogen substitutions into AIE active luminogens enables a facile approach for exploring new intriguing organic fluorescent dyes.
Electrochemically Enabled Chan-Lam Couplings of Aryl Boronic Acids and Anilines
Wexler, Ryan P.,Nuhant, Philippe,Senter, Timothy J.,Gale-Day, Zachary J.
supporting information, p. 4540 - 4543 (2019/06/27)
The Chan-Lam reaction remains a highly utilized transformation for C-N bond formation. However, anilines remain problematic substrates due to their lower nucleophilicity. To address this problem, we developed an electrochemically mediated Chan-Lam coupling of aryl boronic acids and amines utilizing a dual copper anode/cathode system. The mild conditions identified have enabled the preparation of a wide range of functionalized biarylanilines in good yields and chemoselectivities.
Amination of Aryl Boronic Acids with Alkylnitrites: A Convenient Complement to Cu-Promoted Reductive Amination
Levitskiy, Oleg A.,Magdesieva, Tatiana V.
, p. 10028 - 10032 (2019/12/24)
Copper-catalyzed amination of aryl boronic acids with alkylnitrites leading to symmetrical diarylamines with a practical 50-80% yield was elaborated. Two C(sp2)-N bonds are formed in the one-pot process under mild conditions. This new approach to diarylamines is a complement to the Cu-assisted reductive amination of aryl boronic acids avoiding preliminary synthesis of nitrosoarenes. The possible reaction scheme based on quantum chemical calculations was suggested, clarifying key intermediates.
C-Terminal Bioconjugation of Peptides through Photoredox Catalyzed Decarboxylative Alkynylation
Garreau, Marion,Le Vaillant, Franck,Waser, Jerome
supporting information, p. 8182 - 8186 (2019/05/21)
We report the first decarboxylative alkynylation of the C-terminus of peptides starting from free carboxylic acids. The reaction is fast, metal-free, and proceeds cleanly to afford alkynylated peptides with a broad tolerance for the C-terminal amino acid. By the use of hypervalent iodine reagents, the introduction of a broad range of functional groups was successful. C-terminal selectivity was achieved by differentiation of the oxidation potentials of the carboxylic acids based on the use of fine-tuned organic dyes.
PREPARATION OF SECONDARY AMINES WITH ELECTROPHILIC N-LINCHPIN REAGENTS
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Page/Page column 101-102, (2018/12/13)
In one aspect, the present disclosure provides methods of preparing a secondary amine. In some embodiments, the secondary amine comprises two different groups or two identifical groups. Also provided herein are compositions for use in the preparation of the secondary amine.
High Catalytic Activity of Peptide Nanofibres Decorated with Ni and Cu Nanoparticles for the Synthesis of 5-Substituted 1H-Tetrazoles and N-Arylation of Amines
Ghorbani-Choghamarani, Arash,Taherinia, Zahra
, p. 1127 - 1137 (2017/10/10)
A rapid development of a new methodology for decarboxylative N-arylation of carboxylic acids and the preparation of 5-substituted 1H-tetrazoles catalysed by peptide nanofibres decorated with Cu and Ni nanoparticles is presented. Compared with conventional aryl halides, benzoic acids are extremely interesting and environmentally friendly options for the synthesis of secondary aryl amines.
