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1.
To investigate the effect of organic anions on the coordination frameworks, we synthesized five new complexes, namely, {[Zn3(μ-OH2)2(btc)2(btx)3]·4H2O}n (1), [Zn(bdc)(btx)]n (2), {[Ag8(3,5-pydc)4(btx)4]·8H2O}n (3), [Ag(2,6-Hpydc)(btx)]n (4) and [Cd2(μ2-OH2)(2,6-pydc)2(btx)]n (5) (H2bdc = 1,4-benzenedicarboxylic acid; H3btc = 1,3,5-benzenetricarboxylate; 3,5-H2pydc = pyridine-3,5-dicarboxylic acid; 2,6-H2pydc = pyridine-2,6-dicarboxylic acid), which were obtained by the reactions of 1,4-bis(1,2,4-triazol-1-ylmethyl)benzene (btx) as main ligand, and several aromatic polycarboxylate as organic anions with different d10 metal salts. Single crystal structure analysis shows that complexes 1, 3 and 5 possess 3D structures, 2 takes a 2D layer motif, and 4 displays a 1D chain structure. The distinct structures indicate that polycarboxylate anions with the diverse coordination modes and coordination groups can affect the topologies of metal-organic frameworks. In addition, the luminescence measurements reveal that the complexes 1, 2 and 5 exhibit strong fluorescent emissions in the solid state at room temperature. 相似文献
2.
Accurate ab initio coupled-cluster (CCSD) calculations have been used to evaluate systematically the E-E bond lengths, homonuclear dissociation energies, and force constants of a series of fluorine-substituted ethane homologues H3 − nFnE-EH3 − nFn (n=0-3), H3E-EF3, and H3E-EH2F (E=C, Si, Ge, Sn) in their staggered ethane-like conformations. The pronounced lack of correlation between bond lengths, dissociation energies, and force constants observed previously with E=Sn has also been found for the lighter group 14 homologues. However, each element in the group exhibits a different behavior. Attempts are made to interpret the findings in the context of electronegativity, hybridization defects, as well as negative and geminal hyperconjugation. 相似文献
3.
Gui-Lin Wen Ping Liu Chun-Yan Guo Wei-Hong Zhang Qi-Zhen Shi 《Inorganica chimica acta》2009,362(6):1730-2521
Six new coordination polymers based on V-shaped linkage 2,5-bis(4-pyridyl)-1,3,4-thiadiazole (bpt) and transition metal ions, [Co(bpt)(pm)0.5(H2O)]n · 3nH2O (1), [Cu2(bpt)(pm)(H2O)4]n (2), [Co(bpt)(pydc)]n · 2nCHCl3 · nH2O (3), [Cu2(bpt)(pydc)2(H2O)2]n (4), [Cu2(bpt)(pydco)2(H2O)2]n · nH2O (5) and [Cd(bpt)(pydco)]n (6) (H4pm = pyromellitic acid, H2pydc = pyridine-2,6-dicarboxylic acid, H2pydco = pyridine-2,6-dicarboxylic acid N-oxide), have been synthesized under the intervention of various polycarboxylate ligands. Complex 1 exhibits a 3-D 4-connected structure with 1-D nanosized open channels encapsulated lots of water molecules. Complex 2 represents a 2-D grid containing two types of rectangular windows. When pydc and pydco instead of pm, complexes 3 and 6 were obtained with highly undulated 2-D layers. The interlayers of 3 are filled with two kinds of solvent molecules, whereas 6 is a double-layered framework without free molecules. Complexes 4 and 5 consist of two distinct 1-D infinite chains held together to form different 2-D supramolecular networks. Importantly, bpt spacer shows changeful conformational geometries and generates complicated crystalline architectures with the introduction of polycarboxylate ligands. Additionally, thermal stability of complexes 1, 3 and 5, fluorescent properties of 6 and X-ray powder diffraction of 1 have also been investigated. 相似文献
4.
Lei Gou Zhong-Xi Han Qing-Ran Wu Zhen-Hua Yang Fei Wang Gang-Lin Xue 《Inorganica chimica acta》2010,363(11):2590-2599
Five structurally diverse complexes, [Cd2(pyip)2(suc)2]n·1.5nH2O (1), [Zn(pyip)(glu)]n (2), [Cd(pyip)(glu)]n (3), [Zn(pyip)2(adip)2]n·2.5nH2O (4), [Cd3(pyip)2(adip)3]n (5) (pyip = 2-(pyridin-3-yl)-1H-imidazo[4,5-f][1,10]phenan-throline, H2suc = succinic acid, H2glu = glutaric acid, H2adip = adipic acid), have been hydrothermally synthesized. Complexes 1 and 4 are ribbon-like chains, in which pyip ligands attach to the both sides of the chain in pairs. Complex 2 is a one dimensional (1D) wave-like chain, while the pyip ligands attach to only one side of the chain. Complexes 3 and 5 are both two dimensional (2D) networks, in which the dicarboxylate ligands connect the dinuclear or trinuclear CdII units into layers with (4, 4) topological network. The structural differences among these complexes show that the organic acids have important influences on the final structures. 相似文献
5.
Sun L Stenken JA Brunner JE Michel KB Adelsberger JK Yang AY Zhao JJ Musson DG 《Analytical biochemistry》2008,381(2):214-223
It is postulated that elevated tissue concentrations of cortisol may be associated with the development of metabolic syndrome, obesity, and type 2 diabetes. The 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) enzyme regenerates cortisol from inactive cortisone in tissues such as liver and adipose. To better understand the pivotal role of 11β-HSD1 in disease development, an in vivo microdialysis assay coupled with liquid chromatography/tandem mass spectrometry (LC/MS/MS) analysis using stable isotope-labeled (SIL) cortisone as a substrate was developed. This assay overcomes the limitations of existing methodologies that suffer from radioactivity exposure and analytical assay sensitivity and specificity concerns. Analyte extraction efficiencies (Ed) were evaluated by retrodialysis. The conversion of SIL-cortisone to SIL-cortisol in rhesus monkey adipose tissue was studied. Solutions containing 100, 500, and 1000 ng/mL SIL-cortisone were locally delivered through an implanted 30-mm microdialysis probe in adipose tissue. At the delivery rate of 1.0 and 0.5 μL/min, Ed values for SIL-cortisone were between 58.7 ± 5.6% (n = 4) and 72.7 ± 1.3% (n = 4), whereas at 0.3 μL/min Ed reached nearly 100%. The presence of 11β-HSD1 activities in adipose tissue was demonstrated by production of SIL-cortisol during SIL-cortisone infusion. This methodology could be applied to cortisol metabolism studies in tissues of other mammalian species. 相似文献
6.
Xiao-Li Chen Yue-Juan Yao Shuan-Hu Chen Zhong-Xi Han Meng-Lin Yang 《Inorganica chimica acta》2009,362(8):2686-208
To determine the influence of metal ion and the auxiliary ligand on the formation of metal-organic frameworks, six new coordination polymers, {[Mn2(bpdc)(bpy)3(H2O)2] · 2ClO4 · H2O}n (1), {[Mn(bpdc)(dpe)] · CH3OH · 2H2O}n (2), {[Cu(bpdc)(H2O)2]}n (3), {[Zn(bpdc)(H2O)2]}n (4), {[Cd(bpdc)(H2O)3] · 2H2O}n (5), and {[Co(bpdc)(H2O)3] · 0.5dpe · H2O}n (6) (H2bpdc = 2,2′-bipyridine-3,3′-dicarboxylic acid, bpy = 2,2′-bipyridine, dpe = 1,2-di(4-pyridyl) ethylene), have been synthesized and characterized. Compound 1 forms 1D helical chain structure containing two unique MnII ions. In 2, the bridging ligand dpe links Mn-bpdc double zigzag chains to generate a layer possesses rectangular cavities. In 3, bpdc2− ligand connects to three metal centers forming a 2D network. Different from the above compounds, 4 displays a 1D double-wavelike chain. Compound 5 features a helical chain. Compound 6 also displays a helical chain with guest molecule dpe existing in the structure. These diverse structures illustrate rational adjustment of metal ions and the second ligand is a good method for the further design of helical compounds with novel structures and properties. In addition, the magnetic properties of 2, 3 and 6, the thermal stabilities and photoluminescence properties of 4 and 5 were also studied. 相似文献
7.
This study documented the reproductive performance of 210 adult female Formosan sambar deer (FSD, Cervus unicolor swinhoei) from four semi-domesticated deer herds in Taiwan. An extensive analysis of 525 reproductive records from 2000 to 2008, including the conditions of estrus, gestation, and parturition was conducted. The mean ± S.E.M. lengths of the estrous cycle, gestation, and fawning interval were 18.2 ± 0.5 d (n = 56), 258.6 ± 0.3 d (n = 160), and 369.9 ± 2.3 d (n = 122), respectively. Hand breeding was performed between June and December (n = 494), with the majority (93.1%) occurring between July and October (P < 0.05). Fawning occurred from February to September (n = 318), and most frequently (83.0%) between April and June (P < 0.05). Pregnancy rate per mating in FSD hinds was 64.4%. There was a 1.3:1 male-to-female ratio at birth (P < 0.05) among 320 fawns, and only two cases of twinning (0.63%). The postnatal mortality rate was 6.6% (21/320), and the mortality rate in fawns before weaning did not exceed 8% on any farm. Fecundity was enhanced by high pregnancy rates and high offspring survival rates. This study provides baseline information on reproductive performance of FSD, which should be valuable to veterinarians and deer industry personnel for management of FSD on farms in subtropical countries. 相似文献
8.
Marilé Landman James Ramontja Daniela I. Bezuidenhout David C. Liles 《Inorganica chimica acta》2010,363(4):705-9403
The syntheses and structures of homo- and heteronuclear biscarbene complexes with bithiophene spacers were investigated. The complexes were synthesized by lithiation of bithiophene followed by metallation using combinations of the metal precursors MnMeCp(CO)3, W(CO)6, Mo(CO)6 and Cr(CO)6, after which the reaction was quenched with triethyloxonium tetrafluoroborate. This classical Fischer method yielded monocarbene complexes, [MLnC(OEt)C4H2S-C4H3S], ([MLn] = Cr(CO)51a, W(CO)52a or MnMeCp(CO)23a), homonuclear biscarbene complexes, [MLnC(OEt)C4H2S-C4H2SC(OEt)MLn], ([MLn] = Cr(CO)51b, W(CO)52b or MnMeCp(CO)23b) and heteronuclear biscarbene complexes, [MLnC(OEt)C4H2S-C4H2SC(OEt)M′Ln] (1d: [MLn] = Cr(CO)5 and [M′Ln] = W(CO)5; 1e: [MLn] = MnMeCp(CO)2 and [M′Ln] = Cr(CO)5; 1f: [MLn] = Cr(CO)5 and [M′] = Mo(CO)5); 2d: [MLn] = MnMeCp(CO)2 and [M′Ln] = W(CO)5; 3c: [MLn] = MnMeCp(CO)2 and [M′Ln] = Mo(CO)5). Electron density calculations with the gaussian03 software package of 1e revealed a polar rod with the negative pole towards the chromium carbene side, whereas the biscarbenes 1d and 1b showed very little polarity. By-products resulting from activation of the carbene moieties in homonuclear biscarbene complexes included (i) ester-type complexes of the form [MLnC(OEt)C4H2S-C4H2SC(O)OEt], ([MLn] = Cr(CO)51c or W(CO)52c), formed in situ in the reaction of 1b and 2b, (ii) the organic bis-ester compound [EtOC(O)C4H2S-C4H2SC(O)OEt] 4, where both metal moieties had been substituted by oxygen and (iii) the carbon-carbon coupled dimeric bithienyl compound [C4H3S-C4H2SC(O)C(O)C4H2S-C4H3S] 5. By-products obtained from heteronuclear biscarbene reactions contain the former diketo compound (or a derivative) as spacer between two metal carbonyl fragments and have the general formula [MLnC(OEt)C4H2S-C4H2SCR-CR′C4H2S-C4H2SC(OEt)MLn] (5a: [M] = Cr(CO)5, R = OH, R′ = OEt; 5b: [M] = W(CO)5, R = R′ = O; 5c: [M] = Mo(CO)5, R = R′ = O). Reaction of 1d, 1e and 1f with hex-3-yne resulted in the formation of benzannulated products 6a, 6b and 6c. All novel complexes were fully characterized using various spectroscopic techniques. The crystal structures of 1b, 2a and 5 are reported. 相似文献
9.
A new flexible aromatic multithiocarboxylate ligand: 1,4-benzenebis(thioacetic acid) (H2L), was synthesized and introduced to construct three interesting metal-organic frameworks (MOFs) with the photoluminescent properties. Three MOFs were characterized by the elemental analysis, infrared (IR) spectrum, and single crystal X-ray diffraction. [Zn3L3(2,2′-bipy)2]n (1) is a two-dimensional (2D) layered architecture that consists of the linear trinuclear units of Zn atoms. [ZnL(2,2′-bipy)(H2O)]n·0.7nH2O (2) is a one-dimensional (1D) helical chain, which further forms a 2D structure with 30-membered ring with a size of 7.64 × 15.53 Å via O−H···O hydrogen bonds. [ZnL(phen)(H2O)]n·0.35nH2O (3) presents a 2D supramolecular network through the O−H···O interactions. Their thermal and photoluminescent properties in solid state were given. 相似文献
10.
Subal Chandra Manna 《Inorganica chimica acta》2008,361(1):411-416
A three dimensional supramolecular network, {[Co(bpee)(H2O)4] · (tp) · 2(H2O)}n (1) [bpee = trans-1,2 bis(4-pyridyl)ethylene; tp = terephthalate dianion] has been synthesized and characterized by X-ray single crystal structure, magnetic measurement and thermal analysis. The structure determination reveals that the cobalt(II) ions, bridged by bpee and coordinated by four water molecules, give rise to covalently linked 1D polymeric chain. The parallel chains get involved in H-bonding with tp resulting in a 3D architecture. Upon heating 1, which is pink in color, transforms to [Co(bpee)(tp)] (1a, blue). The deaquated species (1a) reverts on keeping in humid atmosphere. Low temperature magnetic data indicate weak antiferromagnetic coupling. 相似文献
11.
Sujittra Youngme Pongthipun Phuengphai Gerard A. van Albada Jan Reedijk 《Inorganica chimica acta》2005,358(11):3267-3271
The synthesis, X-ray structure, spectroscopic and magnetic properties of a zig-zag formato-bridged chain complex with the formula [Cu(dpyam)(μ-O2CH)(OH2)]n(NO3)n (1) (in which dpyam = di-2-pyridylamine) is described.The geometry of the copper(II) ion is distorted square pyramidal with a basal plane consisting of two nitrogen atoms of the dpyam ligand (Cu-N distances 1.987(3) and 2.010(3) Å) and two oxygen atoms of two different formato ligands (Cu-O distances 1.974(2) and 1.975(2) Å). A coordinated water molecule occupies the axial position at a distance of 2.222(3) Å. The copper atoms are bridged unsymmetrically by a formato anion in a syn-anti arrangement, resulting in a polymeric zig-zag chain structure.The magnetic susceptibility measurements (5-280 K) agree with a very weak ferromagnetic chain interaction between the Cu centres with a J value of 0.75 cm−1. 相似文献
12.
Field trials were conducted to increase fertility with AI of flow-sorted, sexed bovine sperm. In the first trial, a novel competitive fertilization approach was used to compare pressures (30 psi vs 50 psi) for sorting sperm. Both X- and Y-sperm were sorted to approximately 95% purity at 30 and at 50 psi; X-50 + Y-30 (and the converse) were mixed in equal numbers for AI of heifers. Fetal sex divulged which treatment produced the pregnancy; 82% of pregnancies resulted from the 30 psi treatment (P < 0.05). Based on a similar approach, a new-pulsed laser did not damage sperm any more than the previous standard continuous wave laser. In a large field trial, sorting sperm at 40 psi increased pregnancy rates in heifers relative to 50 psi (42.3% vs 34.1%, n = 367/group, P < 0.05). Storing sperm for 20 h before sorting at 40 psi decreased pregnancy rates from 42.3% (n = 367) to 36.8% (n = 368; P < 0.05). Breeding heifers with sexed sperm 55-56 h after CIDR removal and PGF2α resulted in 34% (n = 32) pregnant, compared to 49% (n = 35) with fixed-time insemination 67-68 h after CIDR removal (P > 0.1). Lactating dairy cows pre-screened for normal reproductive tracts when OvSynch injections (GnRH, prostaglandin, GnRH) were initiated, had similar (P > 0.1) pregnancy rates to timed AI, with 10 × 106 sexed sperm (43.9%, n = 57), 2 × 106 sexed sperm (40.5%, n = 57) and 10 × 106 unsexed control sperm (55.6%, n = 58). A final field trial with unselected, lactating dairy cows resulted in similar pregnancy rates for 2 × 106 sexed sperm in 0.25 mL straws (25.0%, n = 708) and 0.5 mL straws (24.4%, n = 776), but lower (P < 0.05) than unsexed control sperm (37.7%, n = 713). Younger cows and those >84 days in milk had the highest pregnancy rates for both sexed and unsexed sperm. These studies improved sperm sexing procedures, and provided insight into appropriate commercial use of sexed sperm. 相似文献
13.
Magnitude of sarcomere extension correlates with initial sarcomere length during lengthening of activated single fibers from soleus muscle of rats 总被引:1,自引:0,他引:1
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A laser-diffraction technique was developed that rapidly reports the lengths of sarcomeres (Ls) in serially connected sectors of permeabilized single fibers. The apparatus translates a laser beam along the entire length of a fiber segment within 2 ms, with brief stops at each of 20 contiguous sectors. We tested the hypothesis that during lengthening contractions, when maximally activated fibers are stretched, sectors that contain the longer sarcomeres undergo greater increases in Ls than those containing shorter sarcomeres. Fibers (n = 16) were obtained from the soleus muscles of adult male rats and the middle portions (length = 1.05 ± 0.11 mm; mean ± SD) were investigated. Single stretches of strain 27% and a strain rate of 54% s−1 were initiated at maximum isometric stress and resulted in a 19 ± 9% loss in isometric stress. The data on Ls revealed that 1), the stretch was not distributed uniformly among the sectors, and 2), during the stretch, sectors at long Ls before the stretch elongated more than those at short lengths. The findings support the hypothesis that during stretches of maximally activated skeletal muscles, sarcomeres at longer lengths are more susceptible to damage by excessive strain. 相似文献
14.
Takayoshi Suzuki Toshiaki Tsukuda Sumio Kaizaki Hideo D. Takagi 《Inorganica chimica acta》2005,358(8):2501-2512
Cobalt(III) and rhodium(III) complexes of the series of [MIIICl3 − n(P)3 + n]n+ (M = Co or Rh; n = 0, 1, 2 or 3) have been prepared with the use of 1,1,1-tris(dimethylphosphinomethyl)ethane (tdmme) and mono- or didentate phosphines. The single-crystal X-ray analyses of both series of complexes revealed that the M-P and M-Cl bond lengths were dependent primarily on the strong trans influence of the phosphines, and secondarily on the steric congestion around the metal center resulting from the coordination of several phosphine groups. In fact, the M-P(tdmme) bonds became longer in the order of [MCl3(tdmme)] < [MCl2(tdmme)(PMe3)]+ < [MCl(tdmme)(dmpe)]2+ (dmpe = 1,2-bis(dimethylphosphino)ethane) < [M(tdmme)2]3+ for both CoIII and RhIII series of complexes, while the M-Cl bond lengths were shortened in this order (except for [M(tdmme)2]3+). Such a steric congestion around the metal center can also account for the structural and spectroscopic characteristics of the series of complexes, [MCl(tdmme)(dmpm, dmpe or dmpp)]2+ (dmpm = bis(dimethylphosphino)methane, dmpp = 1,3-bis(dimethylphosphino)propane). The X-ray analysis for [CoCl(tdmme)(dmpm or dmpe)](BF4)2 showed that all Co-P bonds in the dmpm complex were shorter by 0.03-0.04 Å than those in the dmpe complex. Furthermore, the first d-d transition energy of the CoIII complexes and the 1JRh-P(tdmme) coupling constants observed for the RhIII complexes indicated an unusual order in the coordination bond strengths of the didentate diphosphines, i.e., dmpm > dmpe > dmpp. 相似文献
15.
Matthew D. Dembo James S. Jones Shannon M. McCullough Xiaobo Li Howard H. Patterson Robert D. Pike 《Inorganica chimica acta》2010,364(1):102-114
Copper(I) cyanide reacts with various liquid amines and sulfides (L) under solvent-less conditions to form (CuCN)Ln, n = 0.5, 0.57, 0.75, 0.8, 1, 1.25, 1.5, 2. New X-ray structures are reported for L = Py (Py = pyridine, n = 0.57), 2-MePy (n = 1), 3-EtPy (n = 1.5), 2-ClPy (n = 1), 3-ClPy (n = 2), 3-MeOPy (n = 2), 4-tBuPy (n = 1.5), piperidine (n = 1.25), N-methylmorpholine (n = 1), N,N-dimethylcyclohexylamine (n = 1), 1-methylimidazole (n = 3), Me2S (n = 1), and tetrahydrothiophene (n = 1). The amine structures (except for the monomeric 1-methylimidazole complex) reveal 1D CuCN chains decorated with 0-2 L per metal atom. Chain structures observed include zigzag, helical and figure-8 helical. The CuCN-sulfide structures show sulfur-bridging of CuCN chains. In some cases (CuCN)L?1.5 species are transformed to (CuCN)L under vacuum. Thermal analysis shows facile release of ligand, yielding CuCN. Most of the (CuCN)Ln products are photoluminescent, emitting in the visible region. In some cases, coordination of very similar amines results in remarkably different emission spectra. 相似文献
16.
Dmitry Kaluzhny Anna ShchyolkinaMichael Livshits Yury LysovOlga Borisova 《Biophysical chemistry》2009
Human genome is shown to be enriched with (GT)n stretches of lengths from 8 to 20 dinucleotides. Low temperature (T ≤ 10 °C) conformations of d(GT)n oligonucleotides (n = 7, 8, 12, 16, 20) were studied by means of circular dichroism (CD), thermal melting, ethidium bromide (EtBr) probing and single nucleotide substitutions. Rotational relaxation times for EtBr:d(GT)n complexes confirmed a monomolecular state of the oligonucleotides. CD spectra indicated involvement of all guanines of d(GT)8 and d(GT)16 in G-quartets, while dT(GT)7, d(GT)12 and d(GT)20 were shown to be only partially ordered. The schemes of the d(GT)8 and d(GT)16 folds are suggested. 相似文献
17.
The synthesis and characterization of new bis-aquo platinum(II) complexes of the type [Pt(H2O)(P-P)][OTf]2 (OTf = triflate anion), in which the diphosphine P-P is a series of 1,n-bis-diphenyphosphinoalkanes (1a-d, with n = 1-4), 1,2-bis-(di-n-fluorophenylphosphino)ethanes (2a-c, with n = 2, 4-5) and 1,2-bis-dialkylphosphinoethanes (3a-e), where the alkyl substituents at phosphorus have been systematically changed (dmpe) (3a), (depe) (3b), (dippe) (3c), (dcype) (3d) are reported. These complexes were used as catalysts in the Baeyer-Villiger oxidation of 2-methylcyclohexanone, 2-methylcyclopentanone and cyclobutanone with 35% hydrogen peroxide as an environmentally friendly oxidant. The reactions were performed at 25 °C in a chlorinated solvent/H2O two-phase system. All the investigated catalysts performed better than the corresponding dimeric complexes of general formula [Pt(μ-OH)(P-P)]2[BF4]2 as a consequence of the positive effect imparted by the triflate counter-anion on catalysts speciation. 相似文献
18.
The ferrocene-containing polymer [-fc-B(Br)-]n (6) with an average chain length of ca. 20 repeat units (n = 20) is readily accessible from fc(BBr2)2 and HSiEt3 [fc = (C5H4)2Fe] via a novel polycondensation reaction. Treatment of 6 with excess THF yields the highly soluble alkoxy-substituted derivative [-fc-B(O(CH2)4Br)-]n (10; n = 20). 相似文献
19.
Tatyana I. Rokitskaya Vadim N. Tashlitsky Yuri N. Antonenko Vladimir P. Skulachev 《生物化学与生物物理学报:生物膜》2010,1798(9):1698-17840
High negative electric potential inside mitochondria provides a driving force for mitochondria-targeted delivery of cargo molecules linked to hydrophobic penetrating cations. This principle is utilized in construction of mitochondria-targeted antioxidants (MTA) carrying quinone moieties which produce a number of health benefitting effects by protecting cells and organisms from oxidative stress. Here, a series of penetrating cations including MTA were shown to induce the release of the liposome-entrapped carboxyfluorescein anion (CF), but not of glucose or ATP. The ability to induce the leakage of CF from liposomes strongly depended on the number of carbon atoms in alkyl chain (n) of alkyltriphenylphosphonium and alkylrhodamine derivatives. In particular, the leakage of CF was maximal at n about 10-12 and substantially decreased at n = 16. Organic anions (palmitate, oleate, laurylsulfate) competed with CF for the penetrating cation-induced efflux. The reduced activity of alkylrhodamines with n = 16 or n = 18 as compared to that with n = 12 was ascribed to a lower rate of partitioning of the former into liposomal membranes, because electrical current relaxation studies on planar bilayer lipid membranes showed rather close translocation rate constants for alkylrhodamines with n = 18 and n = 12. Changes in the alkylrhodamine absorption spectra upon anion addition confirmed direct interaction between alkylrhodamines and the anion. Thus, mitochondria-targeted penetrating cations can serve as carriers of hydrophobic anions across bilayer lipid membranes. 相似文献
20.
The influence of a mammalian sterol cholesterol and a plant sterol β-sitosterol on the structural parameters and hydration of bilayers in unilamellar vesicles made of monounsaturated diacylphosphatidylcholines (diCn:1PC, n = 14-22 is the even number of acyl chain carbons) was studied at 30 °C using small-angle neutron scattering (SANS). Recently published advanced model of lipid bilayer as a three-strip structure was used with a triangular shape of polar head group probability distribution (Ku?erka et al., Models to analyze small-angle neutron scattering from unilamellar lipid vesicles, Physical Review E 69 (2004) Art. No. 051903). It was found that 33 mol% of both sterols increased the thickness of diCn:1PC bilayers with n = 18-22 similarly. β-sitosterol increased the thickness of diC14:1PC and diC16:1PC bilayers a little more than cholesterol. Both sterols increased the surface area per unit cell by cca 12 Å2 and the number of water molecules located in the head group region by cca 4 molecules, irrespective to the acyl chain length of diCn:1PC. The structural difference in the side chain between cholesterol and β-sitosterol plays a negligible role in influencing the structural parameters of bilayers studied. 相似文献