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91.
Verdree VT Pakhomov S Su G Allen MW Countryman AC Hammer RP Soper SA 《Journal of fluorescence》2007,17(5):547-563
Strategies are reported that produce symmetrical metal-free and metallo-phthalocyanine dyes, Pc and MPc, respectively, containing
various numbers of water solubilizing carboxylic acid groups on their periphery that provide a dual role by also serving as
functional groups to covalently link primary amine-containing targets to these dyes. In order to induce water compatibility
and to minimize the degree of aggregation, the periphery of the macrocycle was decorated with various numbers of water-solubilizing
groups and/or altering the identity of the metal center. The influence of the number of solubilizing groups and metal center
on the spectral and photophysical properties were evaluated. MPc dyes containing 4, 8, or 16 carboxylic acid groups exhibited
similar absorption and emission maxima (677 and 686 nm, respectively) with the molar absorptivity of the Q-band ∼105 M−1 cm−1. Results indicated that the fluorescence lifetimes and quantum yields varied as a function of the metal center; the degree
of carboxylation did not significantly alter these properties in DMSO, but did mediate the solubility and aggregation states
when placed in aqueous solvents. The water solubilizing groups could also serve as labeling moieties for targets bearing primary
amines. Results showed that the conjugate, produced by covalently linking an MPc to streptavidin through one of its carboxylate
groups, generated a red-shift in the emission maximum with a fluorescence lifetime shorter than that of the native MPc dye. 相似文献
92.
Four studies of the 1H NMR spectrum for the aromatic protons of 4-fluoroaniline between 1958 and 1974 give three very different solutions to the second-order, AA′BB′X, spectrum. A re-evaluation of the second-order spectrum was done at 300 MHz. Simultaneous simulations of the 1H NMR spectrum and 19F NMR spectrum for 4-fluoroaniline were done using WINDNMR-Pro, and a new set of parameters for the six coupling constants was obtained from the optimized simulations. This new set of parameters was used as a basis to evaluate the AA′BB′X spectrum for the aromatic protons in N4-(4′-fluorophenyl)succinamic acid and in N4-(4′-fluorophenyl)-3,3-difluorosuccinamic acid by simultaneous simulations of the 1H NMR spectrum and 19F NMR spectrum for each using WINDNMR-Pro. Formation of the amide bond results in small, but significant, changes in the values for the set of parameters in both molecules. These results confirm that second-order analyses as an AA′BB′X system are required for derivatives of 4-fluoroaniline, rather than first-order analyses that have been used in previous reports. 相似文献
93.
Naeem S Thompson AL White AJ Delaude L Wilton-Ely JD 《Dalton transactions (Cambridge, England : 2003)》2011,40(14):3737-3747
The ruthenium(II) complexes [Ru(R)(κ(2)-S(2)C·IPr)(CO)(PPh(3))(2)](+) (R = CH=CHBu(t), CH=CHC(6)H(4)Me-4, C(C≡CPh)=CHPh) are formed on reaction of IPr·CS(2) with [Ru(R)Cl(CO)(BTD)(PPh(3))(2)] (BTD = 2,1,3-benzothiadiazole) or [Ru(C(C≡CPh)=CHPh)Cl(CO)(PPh(3))(2)] in the presence of ammonium hexafluorophosphate. Similarly, the complexes [Ru(CH=CHC(6)H(4)Me-4)(κ(2)-S(2)C·ICy)(CO)(PPh(3))(2)](+) and [Ru(C(C≡CPh)=CHPh)(κ(2)-S(2)C·ICy)(CO)(PPh(3))(2)](+) are formed in the same manner when ICy·CS(2) is employed. The ligand IMes·CS(2) reacts with [Ru(R)Cl(CO)(BTD)(PPh(3))(2)] to form the compounds [Ru(R)(κ(2)-S(2)C·IMes)(CO)(PPh(3))(2)](+) (R = CH=CHBu(t), CH=CHC(6)H(4)Me-4, C(C≡CPh)=CHPh). Two osmium analogues, [Os(CH=CHC(6)H(4)Me-4)(κ(2)-S(2)C·IMes)(CO)(PPh(3))(2)](+) and [Os(C(C≡CPh)=CHPh)(κ(2)-S(2)C·IMes)(CO)(PPh(3))(2)](+) were also prepared. When the more bulky diisopropylphenyl derivative IDip·CS(2) is used, an unusual product, [Ru(κ(2)-SC(H)S(CH=CHC(6)H(4)Me-4)·IDip)Cl(CO)(PPh(3))(2)](+), with a migrated vinyl group, is obtained. Over extended reaction times, [Ru(CH=CHC(6)H(4)Me-4)Cl(BTD)(CO)(PPh(3))(2)] also reacts with IMes·CS(2) and NH(4)PF(6) to yield the analogous product [Ru{κ(2)-SC(H)S(CH=CHC(6)H(4)Me-4)·IMes}Cl(CO)(PPh(3))(2)](+)via the intermediate [Ru(CH=CHC(6)H(4)Me-4)(κ(2)-S(2)C·IMes)(CO)(PPh(3))(2)](+). Structural studies are reported for [Ru(CH=CHC(6)H(4)Me-4)(κ(2)-S(2)C·IPr)(CO)(PPh(3))(2)]PF(6) and [Ru(C(C≡CPh)=CHPh)(κ(2)-S(2)C·ICy)(CO)(PPh(3))(2)]PF(6). 相似文献
94.
Janjua NK Shaheen A Yaqub A Perveen F Sabahat S Mumtaz M Jacob C Ba LA Mohammed HA 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2011,79(5):1600-1604
Interactional studies of new flavonoid derivatives (Fl) with chicken blood ds.DNA were investigated spectrophotometrically in DMSO-H2O (9:1 v/v) at various temperatures. Spectral parameters suggest considerable binding between the flavonoid derivatives studied and ds.DNA. The binding constant values lie in the enhanced-binding range. Thermodynamic parameters obtained from UV studies also point to strong spontaneous binding of Fl with ds.DNA. Viscometric studies complimented the UV results where a small linear increase in relative viscosity of the DNA solution was observed with added optimal flavonoid concentration. An overall mixed mode of interaction (intercalative plus groove binding) is proposed between DNA and flavonoids. Conclusively, investigated flavonoid derivatives are found to be strong DNA binders and seem to be promising drug candidates like their natural analogues. 相似文献
95.
Lorraine E. Combettes Dr. Marie Schuler Rakesh Patel Baltasar Bonillo Dr. Barbara Odell Dr. Amber L. Thompson Dr. Tim D. W. Claridge Prof. Véronique Gouverneur 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(41):13126-13132
Various 3‐fluoropyrrolidines and 4‐fluoropyrrolidin‐2‐ones were prepared by 5‐exo‐trig iodocyclisation from allylic fluorides bearing a pending nitrogen nucleophile. These bench‐stable precursors were made accessible upon electrophilic fluorination of the corresponding allylsilanes. The presence of the allylic fluorine substituent induces syn‐stereocontrol upon iodocyclisation with diastereomeric ratios ranging from 10:1 to > 20:1 for all N‐tosyl‐3‐fluoropent‐4‐en‐1‐amines and amides. The sense and level of stereocontrol is strikingly similar to the corresponding iodocyclisation of structurally related allylic fluorides bearing pending oxygen nucleophiles. These results suggest that the syn selectivity observed upon ring closure involves I2–π complexes with the fluorine positioned inside. 相似文献
96.
HM Aitken AN Hancock CH Schiesser 《Chemical communications (Cambridge, England)》2012,48(67):8326-8328
High level calculations suggest that homolytic substitution (S(H)2) by alkyl radicals at sulfur proceeds through a mechanism that is assisted and dominated by LP → SOMO interactions; in the absence of these interactions, S(H)2 chemistry at sulfur is predicted to be virtually impossible. G3(MP2)-RAD calculations suggest that cyclization of the tert-butylsulfonylbutyl radical 2 (n = 2) proceeds with a rate constant of 1.7 × 10(-24) s(-1) at 80°, some 28 orders of magnitude slower than its sulfide cousin (n = 0). 相似文献
97.
Extracellular matrix synthesis and deposition surrounding the developing vasculature are critical for vessel remodeling and maturation events. Although the basement membrane is an integral structure underlying endothelial cells (ECs), few studies, until recently, have been performed to understand its formation in this context. In this review article, we highlight new data demonstrating a corequirement for ECs and pericytes to properly deposit and assemble vascular basement membranes during morphogenic events. In EC only cultures or under conditions whereby pericyte recruitment is blocked, there is a lack of basement membrane assembly, decreased vessel stability (with increased susceptibility to pro-regressive stimuli), and increased EC tube widths (a marker of dysfunctional EC-pericyte interactions). ECs and pericytes both contribute basement membrane components and, furthermore, both cells induce the expression of particular components as well as integrins that recognize them. The EC-derived factors--platelet derived growth factor-BB and heparin binding-epidermal growth factor--are both critical for pericyte recruitment to EC tubes and concomitant vascular basement membrane formation in vitro and in vivo. Thus, heterotypic EC-pericyte interactions play a fundamental role in vascular basement membrane matrix deposition, a critical tube maturation event that is altered in key disease states such as diabetes and cancer. 相似文献
98.
Kirsten?E.?Christensen Kristína?Csatayová Stephen?G.?DaviesEmail author James?A.?Lee Paul?M.?Roberts Amber?L.?Thompson James?E.?Thomson 《Journal of chemical crystallography》2011,41(7):1007-1012
Abstract
Crystals of benzyl (RS,RS,RS)-7-phenylbicyclo[5.1.0]octan-2-ylcarbamate 9 and (RS,RS,RS)-N-[3′-(4″-methylpiperazin-1″-yl)propyl]-N-{5-(4′′′-cyanophenyl)bicyclo[3.1.0]hexan-2-yl}amine dihydrochloride 10·2HCl were synthesised and single crystal X-ray diffraction was used to establish unambiguously the relative configurations within these structures. Compound 9 crystallizes in the orthorhombic space group P2 1 2 1 2 1 with cell parameters of a = 6.85340(10) ?, b = 9.8732(2) ?, c = 27.5407(6) ?, V = 1863.54(6) ?3 and Z = 4. In the crystal structure adjacent molecules are linked by N–H···O=C hydrogen bonds. Compound 10·2HCl crystallizes as the corresponding monohydrate in the monoclinic space group P2 1/n with cell parameters of a = 7.1540(17) ?, b = 39.763(12) ?, c = 8.163(3) ?, β = 91.062(7)°, V = 2321.7(11) ?3 and Z = 4. In the crystal structure adjacent molecules are linked by a series of hydrogen bonds between the ammonium groups, chloride ions and adventitious water molecules. 相似文献99.
The preparation of substituted 4,5-dihydroisoxazoles can be accomplished via the treatment of β,γ-unsaturated oximes with liquid bromine. The reaction provides a convenient route to the highly functionalized title compounds. 相似文献
100.
Abdul Majid Amber Batool Salah Ud-Din Khan Sajjad Haider 《International journal of quantum chemistry》2019,119(14):e25924
First-principles calculations were performed to investigate the vibrational properties of monomers and dimers of titania, silica, and titania-silica hybrid clusters. Density functional theory-based formulism was employed to optimize the geometry at the B3LYP level and calculate the infrared and Raman spectra of the clusters by using the GGA-PBE exchange-correlation functional. It was found that the vibrational spectra of Ti2O4, Si2O4, and TiSiO4 hybrid clusters provide fingerprint information about structures and structural transitions during the formation of cluster structures. In the case of Si2O4 the mode at 410 cm−1 exhibited the largest vibration of Si atoms, whereas in the case of Ti2O4 the mode at 442 cm−1 exhibited the largest vibration of Ti atoms. The hybrid cluster TiSiO4 was structured using two different methods to explore the effects of starting geometry on the structures and vibrational modes of the clusters. The structural properties of the clusters remained unchanged but vibrational modes were found to be different. It is found that Si shows notable vibrations, but the metal atom Ti merely shows any vibration in the case of TiSiO4 hybrid clusters. The low and intermediate frequency modes were stiffened, whereas the three highest frequency modes were softened when the starting geometry of the hybrid clusters was changed from Si2O4 to Ti2O4. 相似文献