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Broad-band near-infrared (NIR) transient absorption (TA) spectroscopy has been used for the first time to probe an all-carbon-bridged organometallic radical cation complex. The compound [{Ru(PPh3)2Cp}2(µ-CCCC)]+ ([1]+) was investigated in dichloromethane and acetonitrile solutions, using laser excitation at 700, 800, 900, and 1000 nm; these wavelengths span the NIR absorption band envelope. The resulting TA spectra were found to be independent of excitation wavelength and consist of an excited state absorption feature with a peak at ca. 1150 nm and the corresponding bleach signal of the ground-state NIR absorption band, which both decay to 0 over the 50 ps time window investigated. Data were analyzed globally and fit collectively for each of the four different excitation wavelengths, with the resulting best fit to a biexponential decay function indicating two processes with slightly different time scales of ca. 1.5 and ca. 9.0 ps involved in the relaxation to the ground state. [ABSTRACT FROM AUTHOR]

Large metal—oxo clusters consistently assume spherical or regular polyhedral morphologies rather than high-aspect-ratio structures. Access to elongated core structures has now been achieved by the reaction of lanthanoid salts with a tetrazole-functionalized calixarene in the presence of a simple carboxylate coligand. The resulting Ln19 and Ln12 clusters are constructed from apex-fused Ln5O6 trigonal bipyramids and are formed consistently under a range of reaction conditions and reagent ratios. Altering the carboxylate coligand structure reliably controls the cluster length, giving access to a new class of rod-like clusters of variable length. [ABSTRACT FROM AUTHOR]

Singlecrystal X-ray diffraction data measured at 100 K for Dianin’scompound (DC) and 18 of its clathrates formed with a wide range ofguest molecules provide considerable insight into the way the hostadjusts to accommodate guest molecules. Detailed information is alsoobtained regarding the location, orientation, and dynamics of theguests in the host cavity. Although all unit cells are closely similarin size, the host undergoes significant change in response to theimprisonment of its various guests. Enclathration typically resultsin a larger cell and cavity volume, but for the small molecules methanol,ethanol, and nitromethane the host actually shrinks significantlyaround the guests in the cavity. In most clathrates, there is evidenceof close contacts between atoms in the guest and the phenol −OHgroup and/or ring of the DC host. The series of clathrates formedby benzene, toluene, and the halobenzenes show the orientation ofthe benzene ring to be progressively modifed by the increasing sizeof the substituent atom or group on the ring in a systematic mannerthat reflects functional group contributions to van der Waals volumes. [ABSTRACT FROM AUTHOR]

Toluene solutions of fullerene C70 and t-Bu-calix[6]arene form a 2:1 inclusion complex that has been structurally authenticated using synchrotron source X-ray diffraction data. Remarkably, the fullerene is not included in the cavity of the calixarene, and this has implications in predicting the structures of fullerene complexes of other calixarenes and container molecules. The fullerenes shroud the exo surface of the calixarene at the van der Waals limit, with the fullerenes arranged into corrugated sheets, with each calixarene interdigitated at the upper rim with the upper rim of two other calixarenes, the macrocycles forming a bilayer separating the sheets of fullerenes. Toluene solutions of fullerene C70 and t-Bu-calix[6]arene form a 2:1 solid-state inclusion complex. The fullerenes shroud the exo surface of the calixarene at the van der Waals limit, with the fullerenes arranged into corrugated sheets, with interdigitated calixarenes through the upper rims forming a bilayer between the sheets of fullerenes. [ABSTRACT FROM AUTHOR]

Herein, we report a Rh(II)-catalyzed reaction between 1-tosyl-1,2,3-triazoles and halohydrins to provide 2,6-substituted 3,4-dihydro-2 H -1,4-oxazines under basic conditions. The reaction is proposed to undergo a rhodium carbenoid 1,3-insertion into O-H followed by an annulation. The scope includes phenyl or alkenyl C4-substituted triazoles and a range of halohydrins using catalytic Rh 2 Oct 4 and K 2 CO 3 . A synthesis of the antimicrobial natural product (±)-chelonin C is also reported using this novel methodology.

Large metal-oxo clusters consistently assume spherical or regular polyhedral morphologies rather than high-aspect-ratio structures. Access to elongated core structures has now been achieved by the reaction of lanthanoid salts with a tetrazole-functionalized calixarene in the presence of a simple carboxylate co-ligand. The resulting Ln19 and Ln12 clusters are constructed from apex-fused Ln5O6 trigonal bipyramids and are formed consistently under a range of reaction conditions and reagent ratios. Altering the carboxylate co-ligand structure reliably controls the cluster length, giving access to a new class of rod-like clusters of variable length.

Hexamethoxy-calix[6]arene has been fully functionalized with p-phosphonic acid groups on the upper rim in 57% yield over three steps, and has been authenticated in the solid state by X-ray diffraction as either a nitrate salt or one of two calcium complexes. The latter differ by the ratio of calcium ions per calixarene, either 3:1 or 4:1. In both structures the coordination sphere of the calcium ions is made up of oxygen atoms from the phosphonic acid groups and from water of crystallization, as part of extended polymeric layers in the extended 3D packing. Hirshfeld surface analysis shows extensive O...H and O...Ca interactions for the phosphonic acid moieties in both calcium structures. MALDI-TOF MS of the hexaphosphonic acid shows nano-arrays consisting of up to a maximum of 28 calixarene units.

Lower rim O-methyl, -n-butyl, and n-octadecyl calix[4]arenes bearing p-phosphonic acid groups on the upper rim have been prepared in high yield, compounds 12-14. Where possible the compounds have been characterized in the solid state using X-ray diffraction, or as the precursor phosphate esters or a cesium salt. The cone conformation ethyl phosphate ester for the octadecyl compound crystallizes in a bi-layer 39.1 A thick which approaches the 40 A of biological membranes. The 1,3-alternate cone conformation of the cesium salt of the O-methyl phosphonic acid has a metal ion coordinated to two methoxy groups, four O-P (two from neighboring calixarenes), and two eta(3)-C(3) moieties from two 1,3-disposed aromatic rings. MALDI-TOF spectra of compounds 12-14 show successive peaks corresponding to 15, 33 and 16 calixarene units, which is consistent with the intra-molecular H-bonding capabilities of the di-protic phosphonic acid groups where the calixarenes are arranged into layers, including bilayers.