Fluorescent CXCR4 chemokine receptor antagonists: metal activated binding

The copper(II) complex of a novel rhodamine-azamacrocycle conjugate binds to the CXCR4 chemokine receptor and competes effectively against anti-CXCR4 monoclonal antibodies. The copper macrocycle unit adopts a trans-II configuration in the solid state.     

A rotaxane mimic of the photoactive yellow protein chromophore environment: effects of hydrogen bonding and mechanical interlocking on a coumaric amide derivative

Hydrogen bonding in a [2]rotaxane is shown to stabilise the phenolate anion of a coumaric amide chromophore by almost 3 pKa units; however, the effect on the UV spectral shift in the anion is small and, significantly given the photochemistry of PYP, despite the hydrogen bonding olefin photoisomerisation in the anionic rotaxane remains heavily suppressed.     

A metal-complex-tolerant CuAAC 'click' protocol exemplified through the preparation of homo- and mixed-metal-coordinated [2]rotaxanes

A series of mono- and bis-metallated [2]rotaxanes has been prepared using a CuAAC 'click' protocol that is compatible with metal-coordinated building blocks and ligands; the methodology provides a general means for appending a metal ion or complex to an organic scaffold via Cu(I)-catalysed 'click' chemistry, even when the molecule contains redox-active or kinetically labile metals or vacant ligand sites.     

Controlled synthesis of a structurally characterized family of sterically constrained heterocyclic alkoxy-modified titanium alkoxides

The reaction of [Ti(mu-ONep)(ONep)3]2 (ONep = OCH2C(CH3)3) with a series of heterocyclic methanol derivatives [tetrahydrofurfuryl alcohol (H-OTHF), thiophene methanol (H-OTPM), or 2-pyridylcarbinol (H-OPy)-collectively termed H-OR*], led to the isolation of a novel family of OR*-substituted titanium alkoxide precursors. Independent of the initial stoichiometry for the H-OTHF reaction, a monosubstituted, dinuclear species was isolated as [(ONep)3Ti(muc-OTHF)]2 (1). For 1, each Ti was octahedrally (Oh) bound by three terminal ONep ligands, one bidentate bridging OTHF ligand (muc-OTHF), and an oxygen from the other muc-OTHF ligand. For the OTPM derivatives, the product was identified as [(ONep)3Ti(mu-OTPM)]2 (2). For this ligand, the soft S atom does not bind to the Ti but the O atom does act as a bridge between the two trigonal bipyramidal bound Ti metal centers. The OPy system yielded (OPy)2Ti(OR)2 independent of the OR and the stoichiometry used [OR = ONep (3), OCHMe2 (4), OCMe3 (5)]. For 3-5, the two OPy ligands chelate to the Oh-bound Ti metal center with two terminal OR ligands. Compounds 1-5 were fully characterized using a variety of analytical techniques. An initial investigation of the proposed chemical stability of the '(OPy)2Ti' moiety of 3-5 to alcoholysis exchange pathways involving (i) alkyl alcohols, (ii) aryl alcohols, (iii) substituted phenols, (iv) H-OR* derivatives, and (v) silanols proved successful through the isolation of a novel family of structurally characterized (OPy)2Ti(OR')2 (7-24) compounds.     

1,2,3-triazolate-bridged tetradecametallic transition metal clusters [M14(L)6O6(OMe)18X6] (M=FeIII, CrIII and VIII/IV) and related compounds: ground-state spins ranging from S=0 to S=25 and spin-enhanced magnetocaloric effect

We report the synthesis, by solvothermal methods, of the tetradecametallic cluster complexes [M14(L)6O6(OMe)18Cl6] (M=FeIII, CrIII) and [V14(L)6O6(OMe)18Cl6-xOx] (L=anion of 1,2,3-triazole or derivative). Crystal structure data are reported for the {M14} complexes [Fe14(C2H2N3)6O6(OMe)18Cl6], [Cr14(bta)6O6(OMe)18Cl6] (btaH=benzotriazole), [V14O6(Me2bta)6(OMe)18Cl6-xOx] [Me2btaH=5,6-Me2-benzotriazole; eight metal sites are VIII, the remainder are disordered between {VIII-Cl}2+ and {VIV=O}2+] and for the distorted [FeIII14O9(OH)(OMe)8(bta)7(MeOH)5(H2O)Cl8] structure that results from non-solvothermal synthetic methods, highlighting the importance of temperature regime in cluster synthesis. Magnetic studies reveal the {Fe14} complexes to have ground state electronic spins of S相似文献   

Aromatic Higher Alcohols in Wine: Implication on Aroma and Palate Attributes during Chardonnay Aging

The higher alcohols 2-phenylethanol, tryptophol, and tyrosol are a group of yeast-derived compounds that have been shown to affect the aroma and flavour of fermented beverages. Five variants of the industrial wine strain AWRI796, previously isolated due to their elevated production of the ‘rose-like aroma’ compound 2-phenylethanol, were characterised during pilot-scale fermentation of a Chardonnay juice. We show that these variants not only increase the concentration of 2-phenylethanol but also modulate the formation of the higher alcohols tryptophol, tyrosol, and methionol, as well as other volatile sulfur compounds derived from methionine, highlighting the connections between yeast nitrogen and sulfur metabolism during fermentation. We also investigate the development of these compounds during wine storage, focusing on the sulfonation of tryptophol. Finally, the sensory properties of wines produced using these strains were quantified at two time points, unravelling differences produced by biologically modulating higher alcohols and the dynamic changes in wine flavour over aging.     

Catalytic "click" rotaxanes: a substoichiometric metal-template pathway to mechanically interlocked architectures

A route to mechanically interlocked architectures that requires only a catalytic quantity of template is described. The strategy utilizes the Cu(I)-catalyzed 1,3-cycloaddition of azides with terminal alkynes. Chelating the Cu(I) to an endotopic-binding macrocycle means that the metal atom binds to the alkyne and azide in such a way that the metal-mediated bond-forming reaction occurs through the cavity of the macrocycle, forming a rotaxane. Addition of pyridine to the reaction mixture enables the Cu(I) to turn over during the reaction, permitting substoichiometric amounts of the metal to be used. The yields are very high for a rotaxane-forming reaction (up to 94% with stoichiometric Cu(I); 82% with 20 mol % of Cu(I)), and the procedure is practically simple to do (no requirement for an inert atmosphere nor dried or distilled solvents).     

Rotaxanes of cyclic peptides

The synthesis of rotaxanes derived from the synthetic peptide macrocycles cyclo(l-ProGly)4 and cyclo(l-ProGly)5 and diammonium threads is described. [2]Rotaxanes are formed in good yields (56-63%), despite the disruption of internal amide-amide hydrogen bonding in the macrocycles.