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21.
Giuliana Biagi Irene Giorgi Oreste Livi Clementina Manera Valerio Scartoni Pier Luigi Barili 《Journal of heterocyclic chemistry》1997,34(3):845-851
This paper continues the synthesis of new 1,2,3-triazolo[1,2-a]benzotriazoles or 2,3-benzo-1,3a,6,6a-tetrazapentalenes to submit to biological assays. The derivatives were obtained by deoxycyclization reactions of appropriate nitrophenyl-1,2,3-triazole derivatives and by thermal decomposition of appropriate azidophenyl-1,2,3-triazoles (Schemes 1 and 2). Some attempts to extend these synthetic routes to the preparation of 1,2,4-triazolo[1,2-a]benzotriazoles (Scheme 3) and 1,2,3-triazolo[1,2-b]-4H-1,2,3-benzo-triazines (Scheme 4) completely failed. 相似文献
22.
Giuliana Biagi Irene Giorgi Oreste Livi Federica Pacchini Valerio Scartoni 《Journal of heterocyclic chemistry》2002,39(5):885-888
The 7‐chloro‐3‐(2‐chlorobenzyl)‐ and 7‐chloro‐3‐(2‐fluorobenzyl)‐1,2,3‐triazolo[4,5‐d]pyrimidines ( 1 and 4 ), by nucleophilic replacement with some hydrazides, gave the corresponding 7‐hydrazidoderivatives ( 2a‐e and 5a‐e ). These, by heating in Dowtherm, underwent an intramolecular cyclization to form the new tricyclic 7‐substituted‐3‐(2‐chlorobenzyl)‐ and 3‐(2‐fluorobenzyl)‐1,2,3‐triazolo[4,5‐e]1,2,4‐triazolo[4,3‐c]pyrimidines ( 3a‐d and 6a‐d ). The 7‐hydrazino‐3‐(2‐chlorobenzyl)‐ and 7‐hydrazino‐3‐(2‐fluorobenzyl)‐triazolo‐pyrimidines ( 9a and 9b ) were also prepared via the corresponding mercapto ( 7a and 7b ) and thiomethyl ( 8a and 8b ) derivatives. 相似文献
23.
Diphenylphosphine oxidatively adds to the ReRe bonds of Re2
X
4(-dppm)2 (X=Cl or Br; dppm=Ph2PCH2PPh2) and Re2Cl4(-dpam)2 (dpam=Ph2AsCH2AsPh2) to afford the dirhenium(III) complexes Re2(-X)(-PPh2)HX
3(-LL)2. The dppm complexes have also been prepared from the reactions of Re2(-O2CCH3)X
4(-dppm)2 with Ph2PH, and a similar strategy has been used to prepare Re2(-Cl)(-PPh2)HCl3(-dmpm)2 (dmpm=Me2PCH2PMe2) from Re2(-O2CCH3)Cl4(dmpm)2. Phenylphosphine likewise reacts with Re2
X
4(-dppm)2 to give Re2(-X)(-PHPh)HX
3(-dppm)2. An X-ray crystal structure determination on Re2(-Cl)(-PPh2)HCl3(-dppm)2 confirms its edge-shared bioctahedral structure. This complex crystallizes in the space group
(No. 148) witha=21.699(3) Å, =84.50(4)°,V=10084(5) Å3, andZ=6. The structure was refined toR=0.049 (R
w
0.069) for 5770 data withI>3.0(I). The Re-Re distance is 2.5918(7) Å. Oxidation of the bromide complex Re2(-Br)(-PPh2)HBr3(-dppm)2 with NOPF6 produces the unusual dirhenium(III, II) cation [Re2(-H)(-Br)[P(O)Ph2]Br2(NO)(-dppm)2]+ which has been structurally characterized as its perrhenate salt, [Re2(-H)(-Br)[P(O)Ph2]Br2(NO)(-dppm)2]ReO4 · 2CH2Cl2. This complex crystallizes in the space group
(No. 2) witha=14.187(7) Å,b=16.419(5) Å,c=16.729(5) Å, =98.76(2)°, =110.11(3)°, =104.66(3)°,V=3414(6) Å3,Z=2. The structure was refined toR=0.040 (R
w
=0.051) for 5736 data withI>3.0(I). The presence of a phosphorus-bound [P(O)Ph2]– ligand, a linear nitrosyl and a bridging hydrido ligand has been confirmed. The Re-Re distance is 2.6273(8) Å. 相似文献
24.
Biodegradable polyurethanes are an interesting alternative to many applications that involve plastics since they can minimize environmental problems caused by the low rates of natural degradation of synthetic polymers. In addition, since waterborne polyurethanes are based on aqueous dispersions, they restrict the use of organic solvents during processing and application of the polymer, thus contributing furthermore to reduce environmental damage. In this work, aqueous anionic polyurethane dispersions (PUD) with tailorable susceptibility for hydrolysis were synthesized by progressively replacing polypropylene glycol (PPG) with a biodegradable polycaprolactone diol (PCL) as soft segments. The hard segments were formed by extending isophorone diisocyanate (IPDI) with hydrazine (HZ). Dimethylol propionic acid (DMPA) was used as ionic center and triethyl amine (TEA) as neutralizer. The degree of phase separation was evaluated mainly by infrared spectroscopy (FTIR) and small angle X-ray scattering (SAXS). The results indicated that phase separation between hard and soft segments of poly(ester-urethane) is more significant than that of poly(ether-urethane). Data obtained from SAXS experiments indicated that phase separation within soft domains can also be present in samples containing both polyester and polyether soft segments. Hydrolytic degradation of the polymers in buffer solution of pH 7.4 and alkaline solution was performed as an initial test. The results showed that the fraction of polyester soft segments in the polyurethanes can be used to tailor the susceptibility of the materials to hydrolytic attack. Polyurethanes having higher contents of polyester were more promptly hydrolytically degraded than polyurethanes containing only polyether segments. 相似文献
25.
An intraindividual study of the characteristics of erythema induced by bath and oral methoxsalen photochemotherapy and narrowband ultraviolet B 总被引:1,自引:0,他引:1
We compared the characteristics of psoralen and ultraviolet A (PUVA) erythema in skin photosensitized by bath or oral methoxsalen in 20 subjects. Erythema was assessed visually and with a reflectance instrument at 24 h intervals for 7 days. In addition, narrowband ultraviolet B (TL-01 UVB) erythema was examined in 19 of these subjects at 4, 8, 12, 24, 48 and 72 h and in another nine subjects at 12, 15, 18, 21 and 24 h. Both bath and oral PUVA exhibited broad erythemal peaks beyond 72 h. For topical PUVA the lowest minimal phototoxic dose (MPD) occurred at 120 and 144 h (P = 0.01 and 0.03 compared with 72 h). Oral PUVA erythema peaked earlier at 96 h: the MPD was significantly lower at 96, 120 and 144 h compared with 72 h (P = 0.001, 0.01 and 0.02, respectively). At 120 h, bath PUVA had a significantly steeper slope compared with oral PUVA. The TL-01 UVB minimal erythema dose was significantly lower at 12 h compared with 24 h (P = 0.019). The majority of subjects were at maximal erythema at 12 h (22 of 28) and 15 h (eight of nine). Our results suggest that peak erythema for bath PUVA, oral PUVA and TL-01 UVB occurs at 120, 96 and 12-15 h, respectively. 相似文献
26.
In this work we present a study of the F+CH(4)-->HF+CH(3) reaction (DeltaHdegrees(298 K)=-32.0 kcal mol(-1)) using different methods of the chemical reaction theory. The ground potential energy surface (PES) is characterized using several ab initio methods. Full-dimensional rate constants have been calculated employing the variational transition state theory and using directly ab initio data. A triatomic analytical representation of the ground PES was derived from ab initio points calculated at the second- and fourth-order M?ller-Plesset levels with the 6-311+G(2df,2pd) basis set, assuming the CH(3) fragment to be a 15 a.m.u. pseudoatom in the fitting process. This is suggested from experiments that indicate that the methyl group is uncoupled to the reaction coordinate. A dynamics study by means of the quasiclassical trajectory (QCT) method and employing this analytical surface was also carried out. The experimental data available on the HF internal states distributions are reproduced by the QCT results. Very recent experimental information about the reaction stereodynamics is also borne out by our QCT calculations. Comparisons with the benchmark F+H(2) and analogous Cl+CH(4) reactions are established throughout. 相似文献
27.
P. Marketos Irene Zambetaki M. Kleidis 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1993,27(1):17-27
The relativistic CI method is used to determine N-electron wavefunctions for the 1s
2 2s
2 2p
2 (3
P
0,3
P
2,1
D
2), 1s
2 2p
4
3
P
2 even levels, and the 1s
22s2p
3 (3
D
1,3
P
1,3
S
1,1
P
1), 1s
22s
22p3s (3
P
1 and1
P
1), 1s
22s
22p3d (3
D
1,3
P
1,1
P
1)J=1 OIII levels. Excitation energies and emission probabilities between these levels are reported in the electric dipole approximation, both for the Coulomb and the Babushkin gauges.ns,
p,np,nd- andnd (n17) numerical basis functions have been used for the construction of CSF's entering the CI expansion for the ASF's of these levels. Radiative matrix elements of the type calculated here within the framework of the relativistic CI method, may be used in laser assisted spectroscopic studies of atoms and ions. 相似文献
28.
Castagnola M Rossetti DV Inzitari R Vitali A Lupi A Zuppi C Cabras T Fadda MB Petruzzelli R Giardina B Messana I 《Electrophoresis》2003,24(5):801-807
Measurements by capillary electrophoresis (CE) of bacitracin A(1) effective mobility at different pH values permitted to estimate the five acidic dissociation constants and the Stokes radii at different protonation stages of the macrocyclic dodecapeptide. The pK(a) values were 3.6 and 4.4 for the two carboxylic groups of the lateral chains of D-Asp-11 and D-Glu-4, respectively, 6.4 for the aza-atom of the imidazole ring of His-10, 7.6 for the amino group of N-terminal Ile-1 and 9.7 for the delta-amino group of D-Orn-7, very close to the values obtained by other researchers by titration experiments. In agreement with a rigid macrocyclic structure the Stokes radii of different protonated forms ranged only between 14.3 and 14.8 A. Best fitting procedures performed on experimental mobility measured at two different pH values (5.50 and 6.72) in the presence of increasing Zn(+2) concentration allowed confirming the model that assumes the binding of Zn(+2) to P(0) peptide form with a 1.5 x 10(3) M(-1) intrinsic association constant. Following to Zn(+2) binding, the pK(a) of the amino group of N-terminal Ile-1 is shifted from 7.6 to 5.9 and the Stokes radius is reduced of about 3 A. The mean charge of the bacitracin A(1)-Zn(+2) complex resulted +1.67 and +1.12 at pH 5.50 and 6.72, respectively. These results suggest that the amino group of N-terminal Ile-1 is not essential for Zn(+2) binding. 相似文献
29.
30.
Irene Carpani Mario Berrettoni Massimo Gazzano 《Journal of solid state chemistry》2006,179(12):3981-3988
A Ni, Al hydrotalcite-like compound (Htlc) has been proven an useful host material for an alternative synthesis of a K+-free mixed hexacyanoferrate Ni1.5FeIII(CN)6, which is very difficult to obtain in bulk. The first stage of the procedure consists in the intercalation of hexacyanoferrate(III) inside the Htlc structure. The intercalated Htlc has been treated with a NiNO3 solution. The obtained material has been characterized by XRD, XAS Raman and FT-IR spectroscopy. The voltammetric response of the compound obtained after the complete solubilization of the Htlc host shows a typical fingerprint of nickel hexacyanoferrate material with a very low level of potassium. Elemental analysis confirmed the absence of K+ and thus the occurrence of K+-free nickel hexacyanoferrate (14% yield). 相似文献