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Theregioselective 1,3-dipolar cycloaddition reaction of alkoxyalkynyl Fischer carbene complex 1with azidomethyl ferrocene 2and with azidomethyl pyrene 4under solvent-freeconditions yielded the triazolyl Fischer carbene complexes 3(C27H21O6N3FeW) and 5(C33H21O6N3W),respectively. The cation complexation properties of these receptorshave been systematically studied using electrochemical and spectroscopictechniques. The exceptional structural feature existing in these receptorsis the presence of a Fischer carbene moiety, connected to the ferroceneor pyrene moiety through a 1,2,3-triazole ring. Receptor 3contains a redox-active ferrocene moiety and is highly selectivetoward Pb2+ion, whereas receptor 5, havinga fluorescent pyrene unit, selectively recognizes Zn2+andCu2+ions. The binding ability of receptor 3can be inferred either from the redox shift (the anodic shift ΔE1/2= 55 mV) or the highly visual output responsefor Pb2+ion. Receptor 5displays considerablechelation-enhanced fluorescence (CHEF) upon binding with Zn2+and Cu2+ions in an aqueous environment. Further, theproposed binding modes of these receptors and their metal cation complexationproperties have been supported by 1H NMR titration andMALDI-MS and a DFT study. [ABSTRACT FROM AUTHOR]

The preparation, characterization, and electronic structure of the first heterometallic μ9-boride cluster [(Cp*Rh)2{Co6(CO)I2}(μ-H)(BH)B)] has been reported. The interstitial boron atom in the title cluster is within the bonding contact of eight metal and one boron atom in a unique tricapped trigonal prism geometry. [ABSTRACT FROM AUTHOR]

Synthesis and structural elucidation of various electron precise group 5 dimetallaheteroboranes have been described. Room temperature reaction of [Cp 2 VCl 2 ] with Li[BH 3 (EPh)], generated from the treatment of LiBH 4 ·THF and Ph 2 E 2 (E = S or Se), for 1 h in toluene, followed by thermolysis, led to the formation of bimetallic complexes [{CpV(μ-EPh)} 2 {μ-η 2 :η 2 -BH 3 E}], 1 and 2 (1: E = S and 2: E = Se), and [{CpV(μ-SePh)} 2 {μ-η 2 :η 2 -BH(OC 4 H 8 )Se}], 3. One of the striking features of these compounds is that they represent a rare class of distorted tetrahedral clusters having bridging hydrogens. Evaluating the skeletal electron pairs and bonding types, compounds 1, 2, and 3 may be considered as isoelectronic with our earlier reported [(CpV) 2 (B 2 H 6 ) 2 ]. In an attempt to synthesize the Nb analogues of 1-3, room temperature reactions of [CpNbCl 4 ] and Li[BH 3 (EPh)] (E = S or Se) were carried out that afforded compounds [{CpNb(μ-EPh)} 2 {μ-η 2 :η 2 -B 2 H 4 E}], 4 and 5 (4: E = S and 5: E = Se). The solid-state X-ray structures of both 4 and 5 exemplify electronically saturated [M 2 B 3 ] systems, and their geometries are analogous to that of [(Cp*MoCl) 2 B 3 H 7 ]. For the extension of this work, reaction of [Cp*TaCl 4 ] (Cp* = η 5 -C 5 Me 5 ) with Li[BH 3 (SePh)] was carried out that yielded a tantalaselenaborane cluster [(Cp*Ta) 2 (μ-Se)B 3 H 6 Se(C 6 H 5 )] (6). All the new compounds have been characterized using 1 H, 11 B{ 1 H}, 13 C{ 1 H} NMR, UV-vis absorption, and IR spectroscopy, mass spectrometry, and X-ray diffraction studies.

Although template-assisted self-assembly methods are very popular in materials and biological systems, they have certain limitations such as lack of tunability and switchable functionality because of the irreversible association of cells and their matrix components. With an aim to achieve more tunability, we have made an attempt to investigate the self-assembly behavior of rod-shaped living bacteria subjected to an external alternating electric field using confocal microscopy. We demonstrate that rod-shaped living bacteria dispersed in a low salinity aqueous medium form different types of reversible freely suspended structures when subjected to an external alternating electric field. At low field strength, an oriented phase is observed where individual bacterium orients with its major axis aligned along the field direction. At intermediate field strength, bacteria align in the form of one-dimensional (1D) chains that lie along the field direction. Further, at high field strength, more bacteria associate with these 1D chains laterally to form a two-dimensional (2D) array. At higher bacterial concentration, these field-induced 2D arrays extend to form three-dimensional columnar structures. These results are discussed in the context of previously reported studies on bacterial self-assembly., Competing Interests: The authors declare no competing financial interest.