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1.
Bhattacharya S Chattopadhyay S Nayak SK Banerjee M 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2005,62(1-3):729-735
Supramolecular complexation of [60]- and [70]fullerenes with 37-allyl-38,39,40,41,42-pentahydroxy-5,11,17,23,29,35-hexa(4-tert butyl)calix[6]arene (I) has been studied in CCl(4) medium by NMR spectrometric method. All of the complexes are found to be stable with 1:1 stoichiometry. Formation constants (K) of the above supramolecular complexes have been determined from systematic variation of NMR chemical shifts of specific protons of I in the presence of [60]- and [70]fullerenes. Trends in the K value suggest that [70]fullerene binds more strongly with I relative to [60]fullerene. Both PM3 and ab initio calculations reveal that the intermolecular interaction in the [70]fullerene/I complex proceeds through quite deep energy minima. 相似文献
2.
Saha A Mukherjee AK 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2005,61(6):1263-1269
Retinol palmitate (1), which is commonly called "Vitamin A palmitate", has been shown to form charge transfer (CT) complexes with a series of electron acceptors including [60]- and [70]fullerenes, and from the trends in CT transition energies the vertical ionization potential of 1 has been estimated to be 7.73eV. Stoichiometries of the fullerene complexes have been shown to be 1(Vitamin 1): 1([70]fullerene) and 1(Vitamin 1): 2([60]fullerene). The enthalpies and entropies of formation of these two complexes have been determined by estimating the formation constants spectrophotometrically at five different temperatures. The complexation phenomenon may be utilised to dissolve the fullerenes in the non-toxic Vitamin A oil and the solution may be used for testing the biological activity of the fullerenes in vivo. 相似文献
3.
Bhattacharya S Nayak SK Chattopadhyay S Banerjee M Mukherjee AK 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2005,61(1-2):321-329
[60]- and [70]fullerenes have been shown to form 1:1 supramolecular complexes with (i) 24,26-dimethoxy-25,27-dihydroxy-5,11,17,23-tetra(4-tert-butyl)calix[4]arene (1) and (ii) 37,39,41-trimethoxy-38,40,42-trihydroxy-5,11,17,23,29,35-hexa(4-tert-butyl)calix[6]arene (2) in CCl(4) medium by absorption spectroscopy. Charge transfer absorption bands of the complexes have been located in each of the cases (except [70]fullerene-2 complex) studied from which the vertical ionisation potential of 1 has been obtained. Formation constants of the complexes have been determined at four different temperatures from which the enthalpies and entropies of formation of the complexes have been obtained. Moreover, the formation constant of [70]fullerene-2 complex is higher than that of the [60]fullerene-1 and [60]fullerene-2 complexes at all the four temperatures studied. This has been accounted in terms of greater cavity size of 2 which is a calix[6]arene compared to 1 which is a calix[4]arene and also by the fact that a high degree of preorganisation takes place in case of 2 through intramolecular H-bonding at its lower rim. 相似文献
4.
Bhattacharya S Ghosh K Banerjee S Banerjee M 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2006,64(1):47-53
We have investigated electron donor-acceptor complexes of [70]fullerene with various polyaromatic molecules (PAM) with different vertical ionization potentials (I(D)(v)). Well defined charge transfer (CT) absorption bands have been located in the visible region. We extract degrees of charge transfer, oscillator and transition dipole strengths by analyzing the transition energy of the CT band as a function of I(D)(v) of the donors studied. The experimental results were explained using a theoretical model that takes into account the interaction between electronic subsystems of PAM with [70]fullerene. Trends in the formation constant for the [70]fullerene/PAM complexes were discussed in terms of enthalpies and entropies of formation. 相似文献
5.
Michio Yamada Gota Murakami Shuhei Kobayashi Yutaka Maeda 《Tetrahedron letters》2017,58(48):4514-4518
The supramolecular interactions of N-methylporphyrin and iridium porphyrin with C60 in toluene solution were investigated using NMR spectroscopy and absorption spectroscopy. Our results demonstrate that both the N-methylation and iridium metalation of porphyrin are effective means to enhance the binding affinity to C60, resulting in 1:1 complexation for N-methylporphyrin/C60 and 2:1 complexation for iridium porphyrin/C60. 相似文献
6.
The linear and nonlinear optical polarizabilities of donor-acceptor (D-pi-A) chromophores in confined geometries of calix[4]arenes are investigated through a model for interacting polar-polarizable molecules. Both the linear polarizability (alpha) and the first hyperpolarizability (beta) decrease with increasing the interdipolar angle, as expected in the oriented-gas picture. However, within the polar-polarizable model we predict deviations from the additive result, irrespective of the interdipolar angle. Depending on the nature of the chromophore, electrostatic intermolecular interactions between polar and polarizable chromophores lead to cooperative damping or enhancement of the optical responses. Specifically, for chromophores whose ground state is dominated by the neutral D-pi-A structure both alpha and beta are suppressed with respect to the prediction of the oriented-gas model, whereas the opposite holds true for chromophores whose ground state is dominated by the zwitterionic D(+)-pi-A(-). These results explain recent experimental data on a calix[4]arene functionalized with a donor-acceptor dye for nonlinear optical applications. Density functional theory calculations on the relevant crystal structure further support our interpretation. 相似文献
7.
S Bhattacharya M Banerjee A K Mukherjee 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2001,57(7):1463-1470
The electron donor-acceptor (EDA) interaction between [60]fullerene and three methylbenzenes, viz., durene, pentamethylbenzene and hexamethylbenzene has been studied in carbon tetrachloride medium at a number of temperatures. It has been found that these methylbenzenes form stable 1:1 EDA complexes with [60]fullerene. Charge transfer (CT) absorption bands of the complexes in the 410-460 nm region are more intense than the usual 420-700 nm absorption band of C60. The CT transition energies (hvCT) of the complexes change systematically with change in the number and position of the methyl groups in the donor molecules (methylbenzenes) and also with the donor ionisation potentials. From an analysis of this variation the electron affinity of C60 has been found to be 2.30 eV and also an inductive effect Hückel parameter of the methyl group has been determined. Formation constants (K) have been determined at three different temperatures from which the enthalpies and entropies of formation of the complexes have been determined. 相似文献
8.
Bhattacharya S Banerjee M Mukherjee AK 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2003,59(13):3147-3158
The absorption spectra of charge-transfer (CT) complexes of [60]fullerene with liquid methylbenzenes, viz. toluene, o-xylene, m-xylene, p-xylene and mesitylene have been investigated in CCl(4) medium. An absorption band due to CT transition is observed in each case in the visible region. The experimental CT transition energies are well correlated (through Mulliken's equation) with the ionisation potentials (I(D)) of the series of methylbenzenes studied. From an analysis of this variation the electron affinity of [60]fullerene has been found to be 2.32 eV. The degrees of charge transfer in the ground state of the complexes have been found to be very low (0.66-0.775%). It has been found that these methylbenzenes form stable 1:1 complexes with [60]fullerene. Formation constants of the complexes have been determined at four different temperatures from which the enthalpies and entropies of formation of the complexes have been obtained. The experimentally determined formation constants of the complexes of [60]fullerene with methylbenzenes exhibit a very good linear free energy relationship (Chem. Rev. 53 (1953) 191). 相似文献
9.
Xiaoping YangChristopher R. Lowe 《Tetrahedron letters》2003,44(7):1359-1362
In this report, the stepwise synthesis of a novel rigid and functionalised macrocycle 2 based on triazine and phenylenediamine linkers, is presented. Poor recognition of the macrocycle 2 for its substrates is observed, which shows experimentally that for the meltriazine based-calix[6]arene system, the binding ability of the melamine moiety gets more benefit from the ring flexibility derived from a xylenediamine linker 1 than from a phenylenediamine linker 2. 相似文献
10.
11.
Mizyed SA Al-Jarrah E Marji D Ashram M 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2007,68(5):1274-1277
Formation of the charge-transfer complexes between various calix[4]crowns (1-4) and [60]fullerene were studied in toluene solution using UV-vis spectrophotometry. The stability constants and the thermodynamic data of the resulting 1:1 complexes were determined and were found to decrease with increasing the size of the crown moiety of the calixcrown. Except the complex of 3, all the complexes were found to be enthalpy stabilized but disfavored in terms of entropy. 相似文献
12.
Ghosh K Semwal A Nayak SK Banerjee SB Banerjee M 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2007,66(4-5):1122-1125
[60]- and [70]Fullerenes have been shown to form 1:1 supramolecular complexes with bis[2-(5,11,17,23,29,35-hexa-tert-butyl-37,38,39,40,41-pentahydroxycalix[6]arenyl-oxy ethyl ether) (1) and 5,11,17,23,29,35-hexa-tert-butyl-37,38,40,41-tetra hydroxyl-39,42-(crown-4)calix[6]arene (2) in CHCl3 medium by electronic absorption spectroscopy. Formation constants (K) of the complexes of [60]- and [70]fullerenes with 1 and 2 have been determined at room temperature from which free energy of formation values of the complexes have been estimated. The very high formation constant value of [60]fullerene/1 complex (5900 dm3 mol-1) in indicative of formation of inclusion complex. Moreover, PM3 calculations reveal that intermolecular interaction between [60]fullerene and 1 proceeds through quite deep energy molecular orbital. 相似文献
13.
Paris E. Georghiou 《Tetrahedron》2006,62(9):2036-2044
Estimations of equilibrium or association constant (KASSOC) values reported by many other groups for the supramolecular complexation between [60]fullerene (‘C60’) with different macrocyclic hosts, in solvents such as toluene or carbon disulfide, for example, is often conducted by UV-vis absorption and/or 1H NMR spectroscopy. In this paper, the complexation behaviour of two calix[4]naphthalene hosts with C60 in toluene and carbon disulfide has been re-examined, using both of these methods. An analysis is presented of the data newly obtained, in light of recent advances and understanding published by others of the limitations of, in particular, the absorption spectroscopic methods. The discussion presented is also intended to aid those who may be unfamiliar with the nuances and limitations of the analytic models involving C60 supramolecular complexation. Also presented is a general mechanism for C60 supramolecular complexation studies, which lay the groundwork for further experiments. 相似文献
14.
15.
Partha Mukherjee Shrabanti Bhattacharya Sandip K. Nayak Subrata Chattopadhyay Sumanta Bhattacharya 《Chemical physics》2009,360(1-3):116-122
A detailed UV–Vis spectrometric and thermodynamic studies were done to look insight into the nature of molecular interactions of the electron donor–acceptor complexes of C60 and C70 with 5,10,15,20-tetrakis(octadecyloxyphenyl)-21H,23H-porphyrin (1) in chloroform and toluene. Charge transfer (CT) absorption bands were located in the visible region and vertical ionization potential of 1 was determined utilizing CT transition energy. Low values of oscillator and transition dipole strengths suggested that the complexes were almost of neutral character in ground states. The high binding constant value for the C70–1 complex indicated high selectivity of 1 molecule towards C70. Experimental as well as theoretically determined of enthalpies of formation value substantiated the trend in K values for fullerene–1 complexes. 相似文献
16.
Hervé G Hahn DU Hervé AC Goodworth KJ Hill AM Hailes HC 《Organic & biomolecular chemistry》2003,1(2):427-435
Methodologies to access water soluble large ringed calixarenes in good yield using efficient synthetic procedures have been investigated. Symmetrical partial functionalisations at the lower rim are described using activated [n]ethylene glycol chains and the addition behaviour contrasted with that of bromoalkanenitriles which proceeds with no observed regioselectivity. Full functionalisations of the calixarenes bearing hydrophilic groups are then investigated and a two-step procedure established which appears to be generally applicable for the addition of different [n]ethylene glycol chains. Furthermore, difunctionalisation under different reaction conditions are described. Throughout, strategies for the characterisation of these high mass compounds are outlined. 相似文献
17.
Iglesias-Sánchez JC Souto B Pastor CJ de Mendoza J Prados P 《The Journal of organic chemistry》2005,70(25):10400-10407
[structure: see text] In this article we describe the selective O-benzylation of para-unsubstituted calix[6]arene 1 in rings 1 and 4 (2a-c) and the subsequent alkylation of phenol groups with alpha-haloesters (methyl esters 3a, 3c, and 3e; tert-butyl esters 3b, 3d, and 3f) to determine the effect of these groups on their conformational behavior. 2D NMR studies at 188 K reveal that compounds 2a-c, 3b, 3d, and 3f are less flexible, showing a 1,2,3-alternate conformation. The same conformation has been observed in the solid state. 相似文献
18.
Dumbbell fullerene 1 and ditopic bisdouble-calix[5]arene 2 were synthesized. Their iterative host-guest complexations create the supramolecular nano network. Scanning electron microscopy revealed the formation of the branched fiber, possessing a length of more than 100 mum and widths of 250-500 nm on a glass plate. More detailed information was given by atomic force microscopy. The formed fibers on a mica plate have widths of 60-90 nm and heights of 1.2-1.9 nm. The nanosize assemblies are probably composed of a bundle of 40-60 polymer chains created by entangling the alkyl side chains with van der Waals interaction. 相似文献
19.
NMR spectrometric studies of complexation of [60]fullerene with series of meso-tetraphenylporphyrins
Bhattacharya S Nayak SK Chattopadhyay S Banerjee M 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2007,66(2):243-249
Extensive 1H NMR spectrometric studies have been done to gain information on the nature of molecular interactions of the supramolecular complexes of [60]fullerene with a series of meso-tetraphenylporphyrins, namely, meso-5,10,15,20-tetraphenylporphyrin (1), meso-5,10,15,20-tetra-2-bromophenyl-porphyrin (2) and meso-5,10,15,20-tetra-2-chlorophenyl-porphyrin (3) in toluene medium. [60]Fullerene has been shown to form 1:1 adducts with the above series of meso-tetraphenylporphyrins. Formation constants (K) for all the complexes have been determined from the systematic variation of the NMR chemical shifts of beta proton of the porphyrin in presence of [60]fullerene. It has been observed that 3 acts as a better donor in forming supramolecular complex with [60]fullerene. 相似文献
20.
A. N. Novikov V. A. Bacherikov Yu. E. Shapiro A. I. Gren 《Journal of Structural Chemistry》2006,47(6):1003-1015
The cone conformation of C 4 symmetry is shown by the Hartree-Fock method (3-21G basis) to be the predominant conformer of calix[4]arene; the compressed cone of C 2 symmetry is the major conformer of calix[6]arene. Using quantum chemical methods we calculated hydrogen bond cleavage energies for calix[4]-(ab initio and density functional methods) and calix[6]arene (ab initio), and also for the complex of calix[4]arene with carbon disulfide. These energies along with structural data point to the cooperative effect of hydrogen bonds. The results of these studies provided an explanation to the greater conformational lability of calix[6]arene compared with calix[4]arene molecules. It is also predicted that the nucleophilic substitution reaction involving calix[6]arene in the presence of weak bases and in aprotic solvents, as well as in the gas phase, will occur via diastereomeric transition states. 相似文献