The nature of ammonium and methylammonium halides in the vapour phase: hydrogen bonding versus proton transfer

The rotational spectra of two symmetric-top isotopomers of the trimethylphosphine–hydrogen chloride dimer have been observed by pulsed-nozzle, Fourier-transform microwave spectroscopy and analysed to give the following ground-state spectroscopic constants: [graphic omitted] The Cl nuclear quadrupole coupling constant χ(35Cl) is used to establish that the description (CH3)3P⋯HCl rather than (CH3)3[graphic omitted]H⋯text-decoration:overlineCl is more appropriate, although a very small extent of proton transfer cannot be ruled out. The former model is used to obtain r(P⋯Cl)= 3.6131(2)A and kσ= 10.48(7) N m–1. A comparison of χ(35Cl) and kσ among members of the series R3Y⋯HCl, where Y = N or P and R = H or CH3, allows the conclusion that the dimers (R = H, Y = P), (R = H, Y = N) and (R = CH3, Y = P) are of a different nature from (R = CH3, Y = N). These conclusions are discussed in the light of estimates of the energetics of the process R3 Y⋯HCl = R3[graphic omitted]H⋯text-decoration:overlineCl.

Rotational spectrum of (CH3)3P⋯HCl and a comparison of properties within the series of axially symmetric dimers R3Y⋯HCl, where Y = N or P and R = H or CH3

Tilden Lecture. The properties of hydrogen-bonded dimers from rotational spectroscopy

Ahnlich und doch auch verschieden sind die B⋅⋅⋅XY- und B⋅⋅⋅HX-Komplexe in der Gasphase, in denen B eine einfache Lewis-Base, XY ein Homo- oder Heterodihalogen- und HX ein Halogenwasserstoffmolekul ist. Dies zeigen beispielsweise die abgebildeten Strukturen von Oxiran⋅⋅⋅ClF und Oxiran⋅⋅⋅HCl. Beide Bindungen sind durch einfache elektrostatische Wechselwirkungen dominiert, unterscheiden sich aber in der Tendenz zur Abwinkelung.

Präreaktive Komplexe der Dihalogene XY mit Lewis‐Basen B in der Gasphase: eine systematische Studie der Halogen‐Analoga B⋅⋅⋅XY der Wasserstoffbrückenbindungen B⋅⋅⋅HX

Gold nanoparticles (AuNPs) are relevant in nanomedicine for drug delivery in the vascular system, where endothelial cells are the first point of contact. We investigated the uptake of 80 nm AuNPs in primary human umbilical vein endothelial cells (HUVECs) by flow cytometry, 3D confocal microscopy, nano-scale 3D-imaging using focused ion beam/scanning electron microscopy (FIB/SEM), and single particle inductively coupled plasma-mass spectrometry (spICP-MS). HUVECs were cultured for 3 h or 24 h in medium with AuNPs in a concentration range of 1.25–10 μg ml−1. There was a concentration-dependent increase of AuNPs inside cells measured by flow cytometry, spICP-MS and 3D confocal microscopy. The latter also showed that AuNPs were located in the cytosol. This was supported by FIB/SEM, showing that AuNPs were located in membrane enclosures in the cytoplasm as single particles or agglomerates of 2–3 or more particles. Pre-treatment with chlorpromazine inhibited the AuNP-uptake in HUVECs, indicating that internalisation occurred mainly by clathrin-mediated endocytosis. Cell activation by exposure to tumour necrosis factor or lipopolysaccharide had a slight or no effect on the uptake of AuNPs, respectively. The AuNP exposure did not influence cell cytotoxicity, whereas the intracellular reactive oxygen species production was slightly increased. In conclusion, the uptake of AuNPs by endothelial cells can be addressed quantitatively by several methods with high throughput and/or high specificity. Uptake of AuNPs in HUVECs occurred mainly by clathrin-mediated endocytosis and trafficking to membrane enclosures in the form of single particles and agglomerates of 2–3 particles.

Uptake of gold nanoparticles in primary human endothelial cells

The ground‐state rotational spectra of the symmetric‐top isotopomers [(CH3)314N, H35Cl], [(CH3)314N, D35Cl], [(CH3)315N, H35Cl], and [(CH3)315N, H37Cl] of a dimer formed between trimethylamine and hydrogen chloride have been observed in the vapor above heated samples of solid trimethylammonium chloride by pulsed‐nozzle, Fourier‐transform, microwave spectroscopy. Spectroscopic constants have been determined in each case and for [(CH3)314N, H35Cl] the values are B0=1800.4605(2) MHz, DJ=0.320(10) kHz, DJK=13.59(11) kHz, χ(35Cl)=−21.625(5) MHz, and χ(14N)=−3.504(5) MHz. The observed rotational constants B0 indicate that the nuclei N, H, and Cl lie along the C3 symmetry axis of the molecule in the order N⋅⋅⋅H⋅⋅⋅Cl with the distance r(N⋅⋅⋅Cl)=2.8164(3) A. A comparison of the values of the nuclear quadrupole coupling constants χ(35Cl) and χ(14N) with those in related dimers and molecules leads to the evocation of some ionic character (CH3)3N +H Cl arising from a significant extent of proton transfer from Cl to ...

C. A. Rego

Papers

An investigation of the trimethylammonium chloride molecule in the vapor phase by pulsed‐nozzle, Fourier‐transform microwave spectroscopy