The role of the inert (lone) pair of electrons in thallium(I) salts is studied by comparison of the compounds [Tl@18-crown-6]+ X- (X = TlI4, ClO4) and [K@18-crown-6]+ ClO4-. In contrast to common introductory chemistry textbook opinions, the paradigm that s-p hybridization is a prerequisite for an inert electron pair to become stereochemically active in compounds of the heavier main group eleme...

After having emerged as primary contenders in the race for highly efficient optoelectronics materials, organolead halide perovskites (OHLP) are now being investigated in the nanoscale regime as promising building blocks with unique properties. For example, unlike their bulk counterpart, quantum dots of OHLP are brightly luminescent, owing to large exciton binding energies that cannot be rationa...

A wide variety of titled compounds, several of which have neuro-protecting properties has been prepared in yields ranging between 70 to 90%. The compounds were identified by 1 HNMR, 13 C NMR, 1D and 2D NOE analysis, and HRMS. An investigation of the effect of certain 5-substitutuents on the E to Z ratios in DMSO-d6 was carried out. The 5nitro and 5-acetyl substituents were not isomerized, where...

Conformational characteristics and configurational properties of poly(1-methylphosphirane) (PMePP) and poly(1-phenylphosphirane) (PPhPP) have been predictively elucidated by the refined rotational isomeric state scheme coupled with ab initio molecular orbital and density functional calculations. The lone pair of the phosphorus atom adopts an sp hybrid orbital. Owing to the high s character (50%...

The longstanding invincibility of vancomycin (VC) – the last line of antimicrobial therapy for lifethreatening Gram-positive infections – has been compromised over the past decade. The most common and best understood mode of resistance, the VanA type, consists of the replacement of an ester O for an amide NH in the peptide target recognized by the glycopeptide antibiotic. VC targets the C-termi...

Negative linear compressibility (NLC), a rare and important mechanical effect with many application potentials, in a crystal of α-BiB3O6 (BIBO) is comprehensively investigated using first-principles calculations and high-pressure synchrotron X-ray diffraction experiments. The results indicate that the BIBO crystal exhibits the second largest NLC among all known inorganic materials over a broad ...

The binding affinity of 4, which incorporates a methylene (CH2) in place of the key linking amide of Ac2-l-Lys-d-Ala-d-Ala, for vancomycin was compared with that of Ac2-l-Lys-d-Ala-d-Ala (3) and Ac2-l-Lys-d-Ala-d-Lac (5). The vancomycin affinity for 4 was approximately 10-fold less than that of 3, but 100-fold greater than that of 5. This suggests that the reduced binding affinity of 5 (4.1 kca...

The Pb(II) atom in the polymeric title compound, {[Pb(C(13)H(11)N(4)O)(CH(3)OH)(2)]ClO(4)}(n), is coordinated by an N'-[1-(pyridin-2-yl-κN)ethyl-idene]isonicotinohydrazidate ligand via O,N,N'-donors and simultaneously bridged by a neighbouring ligand via the isonicotinoyl N atom; two additional sites are occupied by methanol O atoms. The resultant supra-molecular chain is a zigzag along the c a...

Structural distortions in post-transition metal oxides are often explained in terms of the influence of sp hybrid "lone pairs." Evidence is presented here showing that this model must be revised. The electronic structures of prototypically distorted alpha-PbO and alpha-Bi2O3 have been measured by high-resolution x-ray photoemission and soft x-ray emission spectroscopies. In contrast with the ex...

The relative chemical shifts and 2J(PC) coupling constants in the low-temperature limiting spectra of a series of Ph(R,N)PCl compounds [R = Me, Et, PhCH2, ‘Pr and c-Hex] differ for R = primary or secondary. For primary alkyl substituents, the more downfield signal exhibits a large, positive coupling and the more upfield resonance shows a small, negative coupling. These observations are reversed...