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31.
JPC – Journal of Planar Chromatography – Modern TLC - Asensitive, selective, and precise high-performance thin-layer chromatography (HPTLC) method was developed for simultaneous... 相似文献
32.
Arun Kumar Bar Dr. Srinivasarao Raghothama Dr. Dohyun Moon Prof. Partha Sarathi Mukherjee 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(11):3199-3209
Template‐assisted formation of multicomponent Pd6 coordination prisms and formation of their self‐templated triply interlocked Pd12 analogues in the absence of an external template have been established in a single step through Pd? N/Pd? O coordination. Treatment of cis‐[Pd(en)(NO3)2] with K3tma and linear pillar 4,4′‐bpy (en=ethylenediamine, H3tma=benzene‐1,3,5‐tricarboxylic acid, 4,4′‐bpy=4,4′‐bipyridine) gave intercalated coordination cage [{Pd(en)}6(bpy)3(tma)2]2[NO3]12 ( 1 ) exclusively, whereas the same reaction in the presence of H3tma as an aromatic guest gave a H3tma‐encapsulating non‐interlocked discrete Pd6 molecular prism [{Pd(en)}6(bpy)3(tma)2(H3tma)2][NO3]6 ( 2 ). Though the same reaction using cis‐[Pd(NO3)2(pn)] (pn=propane‐1,2‐diamine) instead of cis‐[Pd(en)(NO3)2] gave triply interlocked coordination cage [{Pd(pn)}6(bpy)3(tma)2]2[NO3]12 ( 3 ) along with non‐interlocked Pd6 analogue [{Pd(pn)}6(bpy)3(tma)2](NO3)6 ( 3′ ), and the presence of H3tma as a guest gave H3tma‐encapsulating molecular prism [{Pd(pn)}6(bpy)3(tma)2(H3tma)2][NO3]6 ( 4 ) exclusively. In solution, the amount of 3′ decreases as the temperature is decreased, and in the solid state 3 is the sole product. Notably, an analogous reaction using the relatively short pillar pz (pz=pyrazine) instead of 4,4′‐bpy gave triply interlocked coordination cage [{Pd(pn)}6(pz)3(tma)2]2[NO3]12 ( 5 ) as the single product. Interestingly, the same reaction using slightly more bulky cis‐[Pd(NO3)2(tmen)] (tmen=N,N,N′,N′‐tetramethylethylene diamine) instead of cis‐[Pd(NO3)2(pn)] gave non‐interlocked [{Pd(tmen)}6(pz)3(tma)2][NO3]6 ( 6 ) exclusively. Complexes 1 , 3 , and 5 represent the first examples of template‐free triply interlocked molecular prisms obtained through multicomponent self‐assembly. Formation of the complexes was supported by IR and multinuclear NMR (1H and 13C) spectroscopy. Formation of guest‐encapsulating complexes ( 2 and 4 ) was confirmed by 2D DOSY and ROESY NMR spectroscopic analyses, whereas for complexes 1 , 3 , 5 , and 6 single‐crystal X‐ray diffraction techniques unambiguously confirmed their formation. The gross geometries of H3tma‐encapsulating complexes 2 and 4 were obtained by universal force field (UFF) simulations. 相似文献
33.
A mild, efficient, and solvent‐free protocol for tetrahydropyranylation of alcohols in the presence of a catalytic amount of SnCl2 · 2H2O is reported. Simple filtration of the reaction mixture through a short silica‐gel pad gives the pure products in excellent yields. Depyranylation can also be achieved by adding methanol under similar reaction conditions. 相似文献
34.
Cellulose - This study explores the hybridizing effect of mechano-chemical activated fly-ash (FA) in polypropylene (PP) composites reinforced with sisal fibers. Activation and resistance against... 相似文献
35.
Shyamaprosad Goswami Abhishek Manna Sima Paul Avijit K. Das Prasanta K. Nandi Anup Kumar Maity Partha Saha 《Tetrahedron letters》2014
5(Benzothiazol-2-yl)-4-hydroxyisophthalaldehyde (BHI), an intense ESIPT containing molecule in mixed media loses its properties due to resonance-assisted H-bond (RAHB) in absolute water. Due to resonance-assisted H-bond the o-aldehyde is more reactive than the other one. With addition of cysteine/homocysteine into this solution the o-aldehyde group gets transformed into thiazolidine/thiazine ring, respectively, and the phenolic proton becomes free enough for transfer to nitrogen of the benzothiazole ring in excited state, that is, the ESIPT of BHI is turned on. Thus we can detect cysteine/homocysteine in water as well as in live cells. 相似文献
36.
Size distributions of nanoparticles in the vicinity of synthesis reactors will provide guidelines for safe operation and protection
of workers. Nanoparticle concentrations and size distributions were measured in a research academic laboratory environment
with two different types of gas-phase synthesis reactors under a variety of operating conditions. The variation of total particle
number concentration and size distribution at different distances from the reactor, off-design state of the fume hood, powder
handling during recovery, and maintenance of reactors are established. Significant increases in number concentration were
observed at all the locations during off-design conditions (i.e., failure of the exhaust system). Clearance of nanoparticles
from the work environment was longer under off-design conditions (20 min) compared to that under normal hood operating conditions
(4–6 min). While lower particle number concentrations are observed during operation of furnace aerosol reactors in comparison
to flame aerosol reactors, the handling, processing, and maintenance operations result in elevated concentrations in the work
area. 相似文献
37.
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39.
Surfactant (SDS)‐mediated cleavage of imines was achieved with acetic anhydride to the corresponding carbonyls (aldehydes and ketones) and acetanilides in water at 25–30°C with very good to excellent yields, thus contributing significantly to the green chemistry concept. 相似文献
40.
Bijay K. Mishra Partha Mukherjee Sukalyan Dash Sabita Patel Hari N. Pati 《合成通讯》2013,43(14):2529-2539
Some monomeric and dimeric surfactants with functional head groups have been synthesized from di- and triethanolamine synthons. The treatment of alkyl bromide with triethanolamine resulted in simultaneous N-alkylation and O-alkylation products. However, with diethanolamine, N-alkylated products were obtained, which were further used to synthesize various double-tailed surfactants and gemini surfactants. 相似文献