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31.
A series of novel luminescent cyclometalated Au(III) neutral complexes of the type cis-[(N(∧)C)AuL] [N(∧)C = 2-phenylpyridine (ppy), L = 1,1'-biphenyl (1)] and cis-[(N(∧)C)AuL(2)] [N(∧)C = 2-phenylpyridine (ppy), L = C(6)H(5) (2), C(6)F(5) (3), C(6)H(4)-CF(3)-p (4), 2-C(4)H(3)S (5)]; [N(∧)C = 2-(2-thienyl)pyridine (thpy), L = C(6)H(5) (6), C(6)F(5) (7)]; [N(∧)C = 2-(5-methyl-2-thienyl)pyridine (5 m-thpy), L = C(6)F(5) (8)] were successfully synthesized. The X-ray crystal structures of all compounds except 3 have been determined. These complexes were found to show long-lived emission in solution at room temperature. The emission origins of the complexes have been tentatively assigned to be derived from triplet states predominantly bearing intraligand (IL) character with some perturbation from the metal center. Density functional theory (DFT) calculations were performed to evaluate the stability associated with the complexes and TD-DFT calculations to ascertain the nature of the excited state. Variation of the cyclometalated ligands in the complexes readily leads to the tuning of the nature of the lower energy emissive states. 相似文献
32.
33.
The generalized Kullback-Leibler divergence (K-Ld) in Tsallis statistics [constrained by the additive duality of generalized statistics (dual generalized K-Ld)] is here reconciled with the theory of Bregman divergences for expectations defined by normal averages, within a measure-theoretic framework. Specifically, it is demonstrated that the dual generalized K-Ld is a scaled Bregman divergence. The Pythagorean theorem is derived from the minimum discrimination information principle using the dual generalized K-Ld as the measure of uncertainty, with constraints defined by normal averages. The minimization of the dual generalized K-Ld, with normal averages constraints, is shown to exhibit distinctly unique features. 相似文献
34.
Following a recent report predicting half-metallicity of Co2Cr0.6Fe0.4Al, we have examined point contacts of this material. Large magnetoresistances (up to 80%) have been observed at room temperature in small fields (10 mT). Magnetostriction in these fields is negligible. A spin polarisation of 81% is inferred. Mössbauer spectra show that 90% of the iron is ordered. The magnetisation of the alloy is 3.65μB per formula unit, and its Curie temperature is 665 K. 相似文献
35.
Hematoporphyrin IX dimethyl ester (HPDME), tetraphenylporphyrin (TPP), tetra(4-methoxyphenyl)porphyrin (TMPP), tetra(3,4-dimethoxyphenyl)porphyrin
(TDMPP), tetra(3,4,5-trimethoxyphenyl)porphyrin (TTMPP), tetraanthrylporphyrin (TAP) and tetraacridylporphyrin (TACP), and
their Zn2+, SnX
2
2+
, Pd2+ and Pt2+ complexes have been prepared and characterized. The singlet molecular oxygen quantum yield (ϕΔ) values of the above porphyrins and their metal derivatives in N,N-dimethyl formamide (DMF) have been measured in the presence
of 1,3-diphenylisobenzofuran (DPBF) as1O2 acceptor using steady state technique after correcting for the intensity of light absorbed by the photosensitizers. The ϕΔ values for the free base porphyrins are usually around 0.60. Hematoporphyrin IX dimethyl ester and its metal derivatives
follow the order: HPDME (ϕΔ = 0.60) > Zn HPDME (0.40) > PdHPDME (0.34) > Sn(OH)2 HPDME (0.28) > PtHPDME (0.24). Zinc(II) complexes of tetraarylporphyrins show about 65% efficiency in ϕΔ values are compared to the ϕΔ values of their corresponding free base porphyrins. These results can be explained on the basis of catalyzed intersystem
crossing to the ground state. The ϕλ values of the above free base porphyrins and their metal complexes in DMF in presence of DPBF using single-pulsed laser excitation
technique follow similar trends. 相似文献
36.
Single crystal EPR studies of Mn(II)-doped zinc ammonium phosphate hexahydrate (ZnNH4PC4·6H2O) have been reinvestigated at room temperature. Single crystal rotations along the three orthogonal axes indicate that the
spin Hamiltonian parameters for the interstitial site are:g
xx
= 1.966,g
yy
= 1.972,g
zz
= 1.976;D
xx
= -12.28 mT,D
yy
= -2.09 mT andD
zz
= 14.37 mT;A
xx
= 9.06 mT,A
yy
= 9.06 mT andA
zz
= 11.09 mT;a = -0.11 mT. These parameters differ considerably from the previous report of Chand and Agarwal and indicate the orthorhombic
nature of the paramagnetic impurity. The impurity is found to enter the lattice interstitially, in contrast to earlier prediction
of substitutional position. The percentage covalency of the Mn-0 bond has been estimated. 相似文献
37.
This study investigated the protective effects of the ethanolic extract of Mukia maderaspatana against indomethacin-induced gastric ulcer in rats. Gastric ulceration was induced by single intraperitoneal injection of indomethacin (30 mg/kg b.wt.). M. maderaspatana extract produced significant reduction in gastric mucosal lesions, malondialdehyde and serum tumour necrosis factor-α associated with a significant increase in gastric juice mucin content and gastric mucosal catalase, nitric oxide and prostaglandin E2 levels. The volume and acidity of the gastric juice decreased in pretreated rats. The plant extract was evaluated in the gastric juice of rats, untreated has showed near normal levels in pretreated rats. The M. maderaspatana was able to decrease acidity and increase the mucosal defence in the gastric area, therefore justifying its use as an antiulcerogenic agent. Ranitidine significantly increased pH value and decreased pepsin activity and gastric juice free and total acidity. The anti-ulcer effect was further confirmed histologically. 相似文献
38.
The whole plant of Phyllanthus wightianus (PW) was investigated for the antioxidant effects of three successive extracts: hexane (PWHE), chloroform (PWCE) and methanol (PWME), using standard in vitro models. The PWME exhibited a strong scavenging effect on 2,2-diphenyl-2-picryl hydrazyl (DPPH) free radicals and nitric oxide radical inhibition activity, due to possessing the highest content of tannins. The free radical scavenging effect of PWME was comparable with that of reference antioxidants. The extracts were subjected to isolation of their compounds: isomeric sterol mixture (1) [stigmasterol (1a), compesterol (1b) and β-sitosterol (1c)], fredilin (2), lupeol (3), gallic acid (4), bergenin (5), geraniin (6), corilagin (7) and ellagic acid (8) were established through the use of column chromatographic methods and spectral data. The percentage of tannins was also determined and estimated using the HPLC method. The data suggest that tannins are the active antioxidant compounds of P. wightianus. This study provides proof for the ethnomedical claims and reported biological activities of this plant. The plant therefore has very good therapeutic potential. 相似文献
39.
A series of novel luminescent neutral cyclometalated gold(III) complexes of the type cis-[(N^C)Au(C≡CR)(2)] (R = aryl, silyl groups) having different cyclometalating cores (N^C) have been synthesized by CuI promoted halide to alkynyl metathesis with NEt(3) as in situ deprotonating agent. Along with spectroscopic characterizations (nuclear magnetic resonance and infrared spectroscopies and electrospray ionization mass spectrometry) and elemental analysis, the molecular structures of some of the complexes have been established by single-crystal X-ray diffraction studies. Photophysical studies reveal that the complexes exhibit room-temperature phosphorescence (RTP). Experimental observations and density functional theory calculations qualitatively suggest limited participation of the metal and alkynyl ligands in the lowest energy emitting state. The nature of the emission is mainly governed by metal-perturbed (3)IL(π-π*) transitions originating from the cyclometalate part of the molecule, and its variation readily leads to the tuning of the emission wavelengths. Cyclic voltammetry measurements of selected complexes showed irreversible redox behavior with near-equivalent cathodic peak potential (E(p,c)) assigned to the C^N core. 相似文献
40.
A series of new thiazolyl chalcones, 1‐[2‐amino‐4‐methyl‐1, 3‐thiazol‐5‐yl]‐3‐aryl‐prop‐2‐en‐1‐one were prepared by piperidine mediated Claisen‐Schmidt condensation of thiazolyl ketone with substituted aromatic aldehyde. These chalcones on cyclization gave 2‐amino‐6‐(2‐amino‐4‐methyl‐1,3‐thiazol‐5‐yl)‐4‐aryl‐4H‐pyridine‐3‐carbonitrile and 2‐amino‐6‐(2‐amino‐4‐methyl‐1,3‐thiazol‐5‐yl)‐4‐aryl‐4H‐pyran‐3‐carbonitrile. The results showed that this skeletal framework exhibited marked potency as antimicrobial agents. The most active antibacterial agent was 2‐amino‐6‐(2‐amino‐4‐methyl‐1,3‐thiazol‐5‐yl)‐4‐(4‐chlorophenyl)‐4H‐pyran‐3‐carbonitrile while 2‐amino‐6‐(2‐amino‐4‐methyl‐1,3‐thiazol‐5‐yl)‐4‐(4‐methoyphenyl)‐4H‐pyran‐3‐carbonitrile appeared to be the most active antifungal agent. J. Heterocyclic Chem., (2011). 相似文献