Phase separation, aggregation, and complexation of triton-X100 and bovine serum albumin mixture: A combined cloud point and UV-visible spectroscopic approaches.

Phase separation and aggregation behaviour of triton X-100 (TX-100) and bovine serum albumin (BSA) mixture were investigated using cloud point and UV-visible spectroscopic techniques. The effects of various hydrotropes (HYTs) - namely, sodium salicylate (SS), sodium benzoate (SB), glycerol (Glyc), and 4-aminobenzoic acid (4-ABA) - on the cloud point (CP) of TX-100 + BSA were determined. The obtained CP values for the mixed system in the presence of HYTs followed the order: The measured critical micellization concentration (CMC) values of the TX-100 + BSA mixture were found to be significantly altered with varying amounts of BSA.

Interaction between gastric enzyme pepsin and tetradecyltrimethylammonium bromide in presence of sodium electrolytes: Exploration of micellization behavior.

Pepsin is a proteolytic enzyme used in the treatment of digestive disorders. In this study, we investigated the physicochemical properties of the tetradecyltrimethylammonium bromide (TTAB) and pepsin protein mixture in various sodium salt media within a temperature range of 300.55-320.

Physicochemical parameters and modes of interaction associated with the micelle formation of a mixture of tetradecyltrimethylammonium bromide and cefixime trihydrate: effects of hydrotropes and temperature.

The interaction between an antibiotic drug (cefixime trihydrate (CMT)) and a cationic surfactant (tetradecyltrimethylammonium bromide (TTAB)) was examined in the presence of both ionic and non-ionic hydrotropes (HTs) over the temperature range of 300.55 to 320.55 K.

Aggregation phenomena and physico-chemical properties of tetradecyltrimethylammonium bromide and protein (bovine serum albumin) mixture: Influence of electrolytes and temperature.

It is important for biological, pharmaceutical, and cosmetic industries to understand how proteins and surfactants interact. Herein, the interaction of bovine serum albumin (BSA) with tetradecyltrimethylammonium bromide (TTAB) in different inorganic salts (KCl, KSO, KPO.HO) has been explored through the conductivity measurement method at different temperatures (300.

Association behavior and physico-chemical parameters of a cetylpyridinium bromide and levofloxacin hemihydrate mixture in aqueous and additive media.

The investigation of the micellization of a mixture of cetylpyridinium bromide (CPB) and levofloxacin hemihydrate (LFH) was carried out by a conductivity technique in aqueous and aq. additive mixtures, including NaCl, NaOAc, NaBenz, 4-ABA, and urea. The aggregation behavior of the CPB + LFH mixture was studied considering the variation in additive contents and the change in experimental temperature.

Investigation of the impacts of simple electrolytes and hydrotrope on the interaction of ceftriaxone sodium with cetylpyridinium chloride at numerous study temperatures.

Herein, interactions between cetylpyridinium chloride (CPC) and ceftriaxone sodium (CTS) were investigated applying conductivity technique. Impacts of the nature of additives (e.g.

Reactions of diphosphine-stabilized Os clusters with triphenylantimony: syntheses and structures of new antimony-containing Os clusters Sb-Ph bond cleavage.

The reactivity of the trimetallic clusters [Os(CO)(μ-dppm)] [dppm = bis(diphenylphosphino)methane] and [HOs(CO){μ-PhPCHPPh(CH-μ,σ)}] with triphenylantimony (SbPh) has been examined. [Os(CO)(μ-dppm)] reacts with SbPh in refluxing toluene to yield three new triosmium clusters [Os(CO)(SbPh)(μ-dppm)] (1), [HOs(CO)(SbPh){μ-PhPCHPPh(CH-μ,σ)}] (2), and [HOs(CO)(SbPh)(μ-CH)(μ-SbPh)(μ-dppm)] (3). [HOs(CO){μ-PhPCHPPh(CH-μ,σ)}] reacts with SbPh (excess) at room temperature to afford [Os(CO)(SbPh)(η-Ph)(μ-SbPh)(μ-dppm)] (4) as the sole product.

A new synthetic route for the preparation of [Os(CO)(μ-OH)(μ-H)] and its reaction with bis(diphenylphosphino)methane (dppm): syntheses and X-ray structures of two isomers of [Os(CO)(μ-OH)(μ-H)(μ-dppm)] and [Os(CO)(μ-CO)(μ-O)(μ-dppm)].

The triosmium cluster [Os(CO)(μ-OH)(μ-H)] containing bridging hydride and hydroxyl groups at a common Os-Os edge was obtained in good yield ( 75%) from the hydrolysis of the labile triosmium cluster [Os(CO)(NCMe)] in THF at 67 °C. [Os(CO)(μ-OH)(μ-H)] reacts with dppm at 68 °C to afford the isomeric clusters 1 and 2 with the general formula [Os(CO)(μ-OH)(μ-H)(μ-dppm)] that differ by the disposition of bridging dppm ligand. Cluster 1 is produced exclusively from the reaction of [Os(CO)(μ-OH)(μ-H)] with dppm in CHCl at room temperature in the presence of added MeNO.

Reactions of triosmium and triruthenium clusters with 2-ethynylpyridine: new modes for alkyne C-C bond coupling and C-H bond activation.

The reaction of the trimetallic clusters [HOs(CO)] and [Ru(CO)L] (L = CO, MeCN) with 2-ethynylpyridine has been investigated. Treatment of [HOs(CO)] with excess 2-ethynylpyridine affords [HOs(CO)(μ-CHNCH=CH)] (1), [HOs(CO)(μ-CHNC[double bond, length as m-dash]CH)] (2), [HOs(CO)(μ-CHNC[double bond, length as m-dash]CCO)] (3), and [HOs(CO)(μ-CH[double bond, length as m-dash]CHCHN)] (4) formed through either the direct addition of the Os-H bond across the C[triple bond, length as m-dash]C bond or acetylenic C-H bond activation of the 2-ethynylpyridine substrate. In contrast, the dominant pathway for the reaction between [Ru(CO)] and 2-ethynylpyridine is C-C bond coupling of the alkyne moiety to furnish the triruthenium clusters [Ru(CO)(μ-CO){μ-CHNC[double bond, length as m-dash]CHC(CHN)[double bond, length as m-dash]CH}] (5) and [Ru(CO)(μ-CO){μ-CHNCCHC(CHN)CHCHC(CHN)}] (6).

New molecular architectures containing low-valent cluster centres with di- and trimetalated 2-vinylpyrazine ligands: synthesis and molecular structures of Ru(CO)(μ-CHNCH[double bond, length as m-dash]CH)(μ-H) and Ru(CO)(μ-CHNCH[double bond, length as m-dash]C)(μ-H).

Reaction of 2-vinylpyrazine with Ru(CO) results in multiple C-H bond activations to afford penta- and octa-ruthenium clusters, Ru(CO)(μ-CHNCH[double bond, length as m-dash]CH)(μ-H) (2) and Ru(CO)(μ-CHNCH[double bond, length as m-dash]C)(μ-H) (3), in which a Ru sub-unit is linked to Ru and Ru centres di- and tri-metalated 2-vinylpyrazine ligands, exhibiting novel coordination modes including the loss of ring aromaticity in 2. The bonding of 2 and the mechanism for the fluxional behaviour of the hydrides have been examined by electronic structure calculations.

Experimental and computational preference for phosphine regioselectivity and stereoselective tripodal rotation in HOs(CO)(PPh)(μ-1,2-N,C-η,κ-CHNS).

The site preference for ligand substitution in the benzothiazolate-bridged cluster HOs(CO)(μ-1,2-N,C-η,κ-CHNS) (1) has been investigated using PPh. 1 reacts with PPh in the presence of MeNO to afford the mono- and bisphosphine substituted clusters HOs(CO)(PPh)(μ-1,2-N,C-η,κ-CHNS) (2) and HOs(CO)(PPh)(μ-1,2-N,C-η,κ-CHNS) (3), respectively. 2 exists as a pair of non-interconverting isomers where the PPh ligand is situated at one of the equatorial sites syn to the edge-bridging hydride that shares a common Os-Os bond with the metalated heterocycle.

Mixed-valence dimolybdenum complexes containing hard oxo and soft carbonyl ligands: synthesis, structure, and electrochemistry of Mo(O)(CO)(μ-κ-S(CH)S)(κ-diphosphine).

Mixed-valence dimolybdenum complexes Mo2(O)(CO)2{μ-κ2-S(CH2)nS}2(κ2-Ph2P(CH2)mPPh2) (n = 2, 3; m = 1, 2) (1-4) have been synthesized from one-pot reactions of fac-Mo(CO)3(NCMe)3 and dithiols, HS(CH2)nSH, in the presence of diphosphines. The dimolybdenum framework is supported by two thiolate bridges, with one molybdenum carrying a terminal oxo ligand and the second two carbonyls. The dppm (m = 1) products exist as a pair of diastereomers differing in the relative orientation of the two carbonyls (cis and trans) at the Mo(CO)2(dppm) center, while dppe (m = 2) complexes are found solely as the trans isomers.

Alkyne activation and polyhedral reorganization in benzothiazolate-capped osmium clusters on reaction with diethyl acetylenedicarboxylate (DEAD) and ethyl propiolate.

The reactivity of the face-capped benzothiazolate clusters HOs(CO)[μ-CH(R)NS] (1a, R = H; 1b, R = 2-CH) with alkynes has been investigated. 1a reacts with DEAD at 67 °C to furnish the isomeric alkenyl clusters Os(CO)(μ-CHNS)(μ-EtOCCCHCOEt) (2a and 3a). X-ray crystallographic analyses of 2a and 3a have confirmed the stereoisomeric relationship of these products and the regiospecific polyhedral expansion that follows the formal transfer of the hydride to the coordinated alkyne ligand in HOs(CO)(μ-CHNS)(η-DEAD).

Electrocatalytic proton reduction catalysed by the low-valent tetrairon-oxo cluster [Fe4(CO)10(κ(2)-dppn)(μ4-O)](2-) [dppn = 1,1'-bis(diphenylphosphino)naphthalene].

The 62-electron oxo-capped tetrairon butterfly cluster, Fe4(CO)10(κ(2)-dppn)(μ4-O) (1) {dppn = 1,8-bis(diphenylphosphino)naphthalene}, undergoes reversible one-electron oxidation and reduction events to generate the 61- and 63-electron radicals [Fe4(CO)10(κ(2)-dppn)(μ4-O)](+) (1+) and [Fe4(CO)10(κ(2)-dppn)(μ4-O)](-) (1-) respectively. Addition of a second electron affords the 64-electron cluster [Fe4(CO)10(κ(2)-dppn)(μ4-O)](2-) (1(2-)) which has more limited stability but is stable within the time frame of the electrochemical experiment. While 1 and 1(-1) are inactive as proton reduction catalysts, dianionic 1(2-) is active for the formation of hydrogen from both CHCl2CO2H and CF3CO2H.

Bioinspired Hydrogenase Models: The Mixed-Valence Triiron Complex [Fe(CO)(μ-edt)] and Phosphine Derivatives [Fe(CO) (PPh) (μ-edt)] ( = 1, 2) and [Fe(CO)(κ-diphosphine)(μ-edt)] as Proton Reduction Catalysts.

The mixed-valence triiron complexes [Fe(CO) (PPh) (μ-edt)] ( = 0-2; edt = SCHCHS) and [Fe(CO)(κ-diphosphine)(μ-edt)] (diphosphine = dppv, dppe, dppb, dppn) have been prepared and structurally characterized. All adopt an arrangement of the dithiolate bridges, and PPh substitution occurs at the apical positions of the outer iron atoms, while the diphosphine complexes exist only in the dibasal form in both the solid state and solution. The carbonyl on the central iron atom is semibridging, and this leads to a rotated structure between the bridged diiron center.

Hydrogenase biomimetics: Fe2(CO)4(μ-dppf)(μ-pdt) (dppf = 1,1'-bis(diphenylphosphino)ferrocene) both a proton-reduction and hydrogen oxidation catalyst.

Fe2(CO)4(μ-dppf)(μ-pdt) catalyses the conversion of protons and electrons into hydrogen and also the reverse reaction thus mimicing both types of binuclear hydrogenase enzymes.

Bio-inspired hydrogenase models: mixed-valence triion complexes as proton reduction catalysts.

Mixed-valence triiron complexes Fe(3)(CO)(7-x)(PPh(3))(x)(μ-edt)(2) (x = 0-2) have been prepared and are shown to act as proton reduction catalysts. Catalysis takes place via an ECEC mechanism with a reduced overpotential of ca. 0.

Cluster chemistry in the Noughties: new developments and their relationship to nanoparticles.

Over the past decade, the chemistry of low-valent transition metal clusters has again come to the fore, primarily as a result of the development of nanochemistry and the realization that large clusters are on the cusp of the nano-domain. This perspective focuses on these recent developments in low-valent transition metal cluster chemistry, specifically looking at cluster-nanoparticles, the use of small and medium sized clusters as nanoparticle precursors, the development of clusters as homogeneous catalysts and hydrogen uptake and storage systems, together with fundamental discoveries relating to novel transformations that can take place within the cluster framework.

Tetranuclear group 7/8 mixed-metal and open trinuclear group 7 metal carbonyl clusters bearing bridging 2-mercapto-1-methylimidazole ligands.

The reactivity of group 7 metal dinuclear carbonyl complexes [M(2)(CO)(6)(mu-SN(2)C(4)H(5))(2)] (1, M = Re; 2, M = Mn) toward group 8 metal trinuclear carbonyl clusters were examined. Reactions of 1 and 2 with [Os(3)(CO)(10)(NCMe)(2)] in refluxing benzene furnished the tetranuclear mixed-metal clusters [Os(3)Re(CO)(13)(mu(3)-SN(2)C(4)H(5))] (3) and [Os(3)Mn(CO)(13)(mu(3)-SN(2)C(4)H(5))] (4), respectively. Similar treatment of 1 and 2 with Ru(3)(CO)(12) yielded the ruthenium analogs [Ru(3)Re(CO)(13)(mu(3)-SN(2)C(4)H(5))] (5), and [Ru(3)Mn(CO)(13)(mu(3)-SN(2)C(4)H(5))] (6), but in the case of 2 a secondary product [Mn(3)(CO)(10)(mu-Cl)(mu(3)-SN(2)C(4)H(5))(2)] (7) was also formed.

Reactivity of triruthenium thiophyne and furyne clusters: competitive S-C and P-C bond cleavage reactions and the generation of highly unsymmetrical alkyne ligands.

The synthesis and reactivity of the thiophyne and furyne clusters [Ru3(CO)7(mu-dppm)(mu3-eta2-C4H2E)(mu-P(C4H3E)2)(mu-H)] (E = S, O) is reported. Addition of P(C4H3E)3 to [Ru3(CO)10(mu-dppm)] (1) at room temperature in the presence of Me3NO gives simple substitution products [Ru3(CO)9(mu-dppm)(P(C4H3E)3)] (E = S, 2; E = O, 3). Mild thermolysis in the presence of further Me3NO affords the thiophyne and furyne complexes [Ru3(CO)7(mu-dppm)(mu3-eta2-C4H2E)(mu-P(C4H3E)2)(mu-H)] (E = S, 4; E = O, 6) resulting from both carbon-hydrogen and carbon-phosphorus bond activation.

Ruthenium and osmium carbonyl clusters incorporating stannylene and stannyl ligands.

The reaction of [Ru(3)(CO)(12)] with Ph(3)SnSPh in refluxing benzene furnished the bimetallic Ru-Sn compound [Ru(3)(CO)(8)(mu-SPh)(2)(mu(3)-SnPh(2))(SnPh(3))(2)] which consists of a SnPh(2) stannylene bonded to three Ru atoms to give a planar tetra-metal core, with two peripheral SnPh(3) ligands. The stannylene ligand forms a very short bond to one Ru atom [Sn-Ru 2.538(1) A] and very long bonds to the other two [Sn-Ru 3.

Synthesis, structure, photophysical and electrochemical behavior of 2-amino-anthracene triosmium clusters.

The reactions of 2-amino-anthracene with [Os(CO)(CHCN)] have been studied and the products structurally characterized by spectroscopic, X-ray diffraction, photophysical and electrochemical techniques. At room temperature in CHCl two major, isomeric products are obtained [Os(CO)(μ-η-(N-C(1))-NHCH)(μ-H)] ( 14%) and [Os(CO)(μ-η-(N-C(3))-NHCH)(μ-H)] (, 35%) along with a trace amount of the dihydrido complex [Os(CO)(μ-η-(N-C(3))-NHCH)(μ-H)] (). In refluxing tetrahydrofuran only complexes and are obtained in 24% and 28%, respectively.

Dithiolate complexes of manganese and rhenium: X-ray structure and properties of an unusual mixed valence cluster Mn3(CO)6(mu-eta2-SCH2CH2CH2S)3.

Treatment of Mn(2)(CO)(10) with 3,4-toluenedithiol and 1,2-ethanedithiol in the presence of Me(3)NO.2H(2)O in CH(2)Cl(2) at room temperature afforded the dinuclear complexes Mn(2)(CO)(6)(mu-eta(4)-SC(6)H(3)(CH(3))S-SC(6)H(3)(CH(3))S) (1), and Mn(2)(CO)(6)(mu-eta(4)-SCH(2)CH(2)S-SCH(2)CH(2)S) (2), respectively. Similar reactions of Re(2)(CO)(10) with 3,4-toluenedithiol, 1,2-benzenedithiol, and 1,2-ethanedithiol yielded the dirhenium complexes Re(2)(CO)(6)(mu-eta(4)-SC(6)H(3)(CH(3))S-SC(6)H(3)(CH(3))S) (3), Re(2)(CO)(6)(mu-eta(4)-SC(6)H(4)S-SC(6)H(4)S) (4), and Re(2)(CO)(6)(SCH(2)CH(2)S-SCH(2)CH(2)S) (5), respectively.

Oxidative addition of silanes R3SiH to the unsaturated cluster [Os3(micro-H)[micro3-Ph2PCH2PPh(C6H4)](CO)8]: evidence for reversible silane formation in the dynamic behaviour of [Os3(micro-H)(SiR3)(CO)9(micro-dppm)].

Oxidative addition of the silanes R(3)SiH (R(3)= Ph(3), Et(3), EtMe(2)) to the unsaturated cluster [Os(3)(micro-H)[micro(3)-Ph(2)PCH(2)PPh(C(6)H(4))](CO)(8)] leads to the saturated clusters [Os(3)(micro-H)(SiR(3))(CO)(9)(micro-dppm)](SiR(3)= SiPh(3) 1, SiEt(3) 2 and SiEtMe(2)3) and the unsaturated clusters [Os(3)(micro -H)(2)(SiR(3))[micro(3)-Ph(2)PCH(2)PPh(C(6)H(4))](CO)(7)](SiR(3)= SiPh(3) 4, SiEt(3) 5 and SiEtMe(2)6). Structures are based on spectroscopic evidence and a XRD structure of [Os(3)(micro-H)(SiPh(3))(CO)(9)(micro-dppm)] 1 in which all non-CO ligands are coordinated equatorially and the hydride and the silyl groups are mutually cis. From variable-temperature (1)H NMR spectra of the SiEt(3) compound 2, exchange of the P nuclei is clearly apparent.