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41.
The host-guest chemistry of most inorganic layered solids is limited to ion-exchange reactions. The guest species are either cations or anions to compensate for the charge deficit, either positive or negative, of the inorganic layers. Here, we outline a strategy to include neutral molecules like ortho- and para-chloranil, that are known to be good acceptors in donor-acceptor or charge-transfer complexes, within the galleries of a layered solid. We have succeeded in including neutral ortho- and para-chloranil molecules within the galleries of an Mg-Al layered double hydroxide (LDH) by using charge-transfer interactions with preintercalated p-aminobenzoate ions as the driving force. The p-aminobenzoate ions are introduced in the Mg-Al LDH via ion exchange. The intercalated LDH can adsorb ortho- and para-chloranil from chloroform solutions by forming charge-transfer complexes with the p-aminobenzoate anions present in the galleries. We use X-ray diffraction, spectroscopy, and molecular dynamics simulations to establish the nature of interactions and arrangement of the charge-transfer complex within the galleries of the layered double hydroxide. 相似文献
42.
SK. Musharaf Ali 《Molecular physics》2013,111(4):387-393
We propose a simple hybrid model for the shear viscosity of isotopic fluid mixtures by coupling the contribution of the Stokes–Einstein relation with the existing linear model of Roults's law for the shear viscosity. The calculated values of shear viscosity using this simple hybrid model are found to be in excellent agreement with the molecular dynamics (MD) simulation results. The calculated value of the shear viscosity obtained from the theoretical model as well as the MD simulation increases with increasing mass ratio. 相似文献
43.
Joseph P.Y. Kao Sukumaran Muralidharan Peter Y. Zavalij Steven Fletcher Fengtian Xue Gerald M. Rosen 《Tetrahedron letters》2014
Pyrroloxyls have been reported to exhibit very narrow EPR spectral lines, essential for in vivo imaging. En route to pyrroloxyls, we observed an unexpected Baeyer–Villiger rearrangement, leading to loss of aromaticity and formation of a 4,5-dihydro-1H-ketopyrrole. 相似文献
44.
The effect of Nd3+ concentration on the CW and Q-switched laser performances at 1064 nm from Nd: YVO4 has been studied under diode laser pumping in identical laser configuration. The Nd3+ concentrations used were 1, 2 and 3 at.% in YVO4 crystals. Under the CW operations we have compared the thermal lensing effect, slope efficiencies and also the beam quality
at the fourth-order degeneracy configuration. Q-switching was done with the help of an acousto-optic modulator and we have
compared the pulses obtained from Nd: YVO4 laser with different doping concentration. It was found that the 1 at.%-doped crystal is the best, offering highest optical-to-optical
conversion efficiency (55%), lowest fractional heat load (24%), highest pulse energy (80 μJ) and shortest pulse width (20 ns). It was also found that there was not much difference in performances for 2 and 3 at.%-doped
crystals both in CW and Q-switched configurations. 相似文献
45.
Pryadun R Sukumaran D Bogadi R Atwood JD 《Journal of the American Chemical Society》2004,126(39):12414-12420
A sequence of alkene complexes of platinum, PtCl(2)(PPh(3))(alkene) (alkene = ethylene, propene, 1-butene, cis-2-butene, 1-hexene, 1-octene, and 1-decene), has been prepared. These complexes are characterized by NMR spectroscopy, including assignment of each proton, and X-ray crystal structures of the 1-propene and 1-hexene complexes. Each complex was reacted with diethylamine. For the 1-hexene, 1-octene, and 1-decene complexes, the amine displaces the alkene. For the smaller alkenes, the diethylamine nucleophilically attacks the coordinated alkene. For propene and 1-butene, the low-temperature addition leads to the anti-Markovnikoff nucleophilic attack, which slowly converts at room temperature to the Markovnikoff product. The transformation from anti-Markovnikoff to Markovnikoff addition occurs without diethylamine dissociation. 相似文献
46.
Murali S Kharlanov V Rettig W Tolmachev AI Kropachev AV 《The journal of physical chemistry. A》2005,109(29):6420-6429
Absorption and emission properties of DMABN-F4, the tetrafluoro analogue of DMABN, have been investigated and compared with the parent compound. Unlike in DMABN, this new compound exhibits only a highly solvatochromic and strongly red-shifted charge transfer (CT) fluorescence and is characterized by the absence of an LE band even in nonpolar solvents. This evidences the faster formation of CT in the excited state as compared to DMABN. The low quantum yield values of DMABN-F4 suggest that the high rate of nonradiative decay takes place via internal conversion (IC) rather than intersystem crossing (ISC) as no phosphorescence is observed in rigid glass solvents at 77 K in contrast to DMABN. The emission transition moment and radiative rate constant values of DMABN-F4 in medium and highly polar solvents point to a forbidden emission in the excited state similar to that of DMABN. Electronic structure and twist potentials were also studied by quantum chemical calculations using ab initio and semiempirical methods. In contrast to DMABN, the dimethylamino group in DMABN-F4 is found to be twisted by around 30-50 degrees, but the photophysics are concluded to be analogous to DMABN with the addition of a very fast IC channel. 相似文献
47.
Oligothiophene-Ring-Strapped Perylene Bisimides: Functionalizable Coaxial Donor–Acceptor Macrocycles
Sairam Dnyaneshwar Veer Vivek Chandrakant Wakchaure Kiran Asokan Ruchi Dixit Tanmay Goswami Ramchandra Saha Rajesh Gonnade Hirendra N. Ghosh Sukumaran Santhosh Babu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2023,135(3):e202212934
Aesthetic designs from nature enable new knowledge to be gained and, at the same time, inspire scientific models. In this context, multicomponent macrocycles embody the advantage of precisely positioning the structural units to achieve efficient communication between them. However, the construction of a functionalizable macrocycle for ultrafast charge separation and stabilization has not been attempted. Herein, we report the synthesis, crystal structure, and transient absorption of a new functionalizable macrocycle consisting of an oligothiophene-ring-strapped perylene bisimide. Transient absorption results point to a sequential improvement in charge separation and stabilization from the macrocycle to the corresponding linear dimer and 2D polymer due to the unique design. Our macrocycle design with a supportive spatial arrangement of the donor and acceptor units will inspire the development of more complex synthetic systems with exciting electron-transfer and charge-separation features. 相似文献
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