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排序方式: 共有283条查询结果,搜索用时 15 毫秒
111.
Dr. Kalathil K. Kartha Dr. Naveen Kumar Allampally Prof. Dr. Shiki Yagai Dr. Rodrigo Q. Albuquerque Prof. Dr. Gustavo Fernández 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(39):9230-9236
The supramolecular polymerization of an acid-sensitive pyridyl-based ligand ( L1 ) bearing a photoresponsive azobenzene moiety was elucidated by mechanistic studies. Addition of trifluoroacetic acid (TFA) led to the transformation of the antiparallel H-bonded fibers of L1 in methylcyclohexane into superhelical braid-like fibers stabilized by H-bonding of parallel-stacked monomer units. Interestingly, L1 dimers held together by unconventional pyridine–TFA N⋅⋅⋅H⋅⋅⋅O bridges represent the main structural elements of the assembly. UV-light irradiation caused a strain-driven disassembly and subsequent aggregate reconstruction, which ultimately led to short fibers. The results allowed to understand the mechanism of mutual influence of acid and light stimuli on supramolecular polymerization processes, thus opening up new possibilities to design advanced stimuli-triggered supramolecular systems. 相似文献
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Doddabhadrappla Gowda Prakasha Naveen Sanju Malagi Pundikala Veeresha 《Mathematical Methods in the Applied Sciences》2020,43(17):9654-9670
In this paper, we find the solution and analyse the behaviour of the obtained results for the nonlinear Schrödinger-Boussinesq equations using q -homotopy analysis transform method (q -HATM) within the frame of fractional order. The considered system describes the interfaces between intermediate long and short waves. The projected fractional operator is proposed with the help of Mittag-Leffler function to incorporate the nonsingular kernel to the system. The projected algorithm is a modified and accurate method with the help of Laplace transform. The convergence analysis is presented with the help of the fixed point theorem in the form existence and uniqueness. To validate and illustrate the effectiveness of the algorithm considered, we exemplified considered system with respect of arbitrary order. Further, the behaviour of achieved results is captured in contour and 3D plots for distinct arbitrary order. The results show that the projected scheme is very effective, highly methodical and easy to apply for complex and nonlinear systems and help us to captured associated behaviour diverse classes of the phenomenon. 相似文献
115.
Numerical Algorithms - In this article, a class of upwind schemes is proposed for systems, each of which yields an incomplete set of linearly independent eigenvectors. The theory of Jordan... 相似文献
116.
A stereoselective synthesis of the hexahydroazepine core of (−)-balanol is described. The key step of the route includes the bromosulfonamidation of an olefin using the intramolecular sulfilimine group as the nucleophile and the Pummerer ene reaction. 相似文献
117.
Raghavan S Reddy SR Tony KA Kumar ChN Varma AK Nangia A 《The Journal of organic chemistry》2002,67(16):5838-5841
Bromohydrins have been prepared from beta-methyl-gamma,delta-unsaturated sulfoxides with high regio- and stereoselectivity. The reaction proceeds via neighboring group participation of the sulfinyl moiety with inversion of sulfoxide configuration as proven by an (18)O labeling study and X-ray crystallography. 相似文献
118.
Amit Aran Naveen K. Nishchal Vinod K. Beri Arun K. Gupta 《Optics and Lasers in Engineering》2008,46(1):34-41
In this paper, we report a log-polar transform-based filter for in-plane rotation and scale-invariant target recognition. The log-polar transform is a known space-invariant image representation used in several image vision systems to eliminate the effects of scale and rotation in an image. In case of in-plane rotation invariance, peaks shift horizontally, while in case of scale invariance, peaks shift vertically. For full out-of-plane rotation-invariance (0–360°), log-polar transformed images are used to train the wavelet-modified maximum average correlation height (WaveMACH) filter. Correlation peak height and peak-to-sidelobe ratio have been calculated as metrics of goodness of the log-polar transform-based WaveMACH filter. This filter would reduce the memory requirement for filter storage in a practical system. Simulation results have been presented. 相似文献
119.
Sanjay Singh Rina Mahato Pragya Sharma Naveen Yadav Nagaraju Vodnala Dr. Chinmoy Kumar Hazra 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(14):e202104545
This work describes a mild and robust double hydroarylation strategy for the synthesis of symmetrical /unsymmetrical diaryl- and triarylmethanes in excellent yields using Lambert salt (0.2–1.0 mol%). Despite the anticipated challenges associated with controlling selective product formation, unsymmetrical diaryl- and triarylmethanes products are obtained unprecedentedly. A highly efficient gram scale reaction has also been reported (TON for symmetrical product=475 and for unsymmetrical product=390). The synthetic utility of the methodology is demonstrated by the preparation of several unexplored diaryl- and triarylmethane-based biologically relevant molecules, such as arundine, vibrindole A, turbomycin B, and certain anti-inflammatory agents. A total synthesis of an anti-breast-cancer agent is also demonstrated. Control experiments, Hammett analysis, HRMS and GC-MS studies reveal the reaction intermediates and reaction mechanism. 相似文献
120.
Naveen Yadav Aparna Tyagi Jabir Khan Chinmoy Kumar Hazra 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(64):e202201938
An unprecedented, Brookhart's acid-catalyzed temperature-switchable regioselective divergent approach for N-alkylation of arylamines and heterocyclic amines by utilising cyclopropylcarbinols is presented herein. The reaction offers N-alkylated cyclopropyl derivatives and homoallyl amines by employing 2.5 mol% catalyst loading at different temperatures in excellent regioselectivity and yields. This method has shown to be relevant with a wide range of cyclopropylcarbinols, including aliphatic ones. Several control experiments and spectroscopic studies have been performed to gain insight into the reaction mechanism. Further, the synthetic utility of the protocol has also been described. 相似文献