Helium Nanodroplet Isolation Spectroscopy In An Undergraduate Teaching Laboratory

A home-built helium nanodroplet isolation spectrometer has been utilized by undergraduate students in course-based experiments to investigate the rovibrational dynamics of small molecules. Helium nanodroplets are well known to simplify the spectroscopy of embedded molecules owing to their low temperature (0.4 K) and weakly interacting nature. In the infrared spectral region, this results in a small number of rotationally resolved lines that can often be collected and analyzed in several lab periods. We demonstrate the advantages of using this technique in an upper-level undergraduate chemistry course for which the laser spectroscopy of helium solvated $^{13}$C-labelled formic acid was investigated for the first time

Far-infrared spectroscopy of syn-vinyl alcohol

Vinyl alcohol has been extensively studied in both the microwave\footnote{S. Saito, Chem. Phys. Lett. 42, 3 (1976)}$^{,}$\footnote{M. Rodler et al., J. Am. Chem. Soc. 106, 4029 (1948)} and mid-IR\footnote{Y. Koga et al., J. Mol. Spec. 145, 315 (1991)}$^{,}$\footnote{D-L. Joo et al., J. Mol. Spec. 197, 68 (1999)} spectral regions, where 9 out of 15 vibrational modes have been identified. Here we present the first far-IR spectrum of vinyl alcohol, collected below 700 \wn at the Australian Synchrotron. The high resolution (0.001 \wn) spectrum reveals the \nub{11} and \nub{15} fundamentals of syn-vinyl alcohol at 489 \wn and 407 \wn, in addition to two hot bands of the \nub{15} mode at 369 \wn and 323 \wn. High \textit{J} transitions in the R-branch of the \nub{15} band were found to be perturbed by an \textit{a}-axis Coriolis interaction with the nearby \nub{11} state. The \nub{15} torsional mode of \textit{syn}-vinyl alcohol was fit using a Watson's A-reduced Hamiltonian to yield rotational, centrifugal distortion, and Coriolis coupling parameters

Mid-infrared signatures of hydroxyl containing water clusters: Infrared laser Stark spectroscopy of OH–H2O and OH(D2O)n (n = 1-3)

Small water clusters containing a single hydroxyl radical are synthesized in liquid helium droplets. The OH–H2O and OH(D2O)n clusters (n = 1-3) are probed with infrared laser spectroscopy in the vicinity of the hydroxyl radical OH stretch vibration. Experimental band origins are qualitatively consistent with ab initio calculations of the global minimum structures; however, frequency shifts from isolated OH are significantly over-predicted by both B3LYP and MP2 methods. An effective Hamiltonian that accounts for partial quenching of electronic angular momentum is used to analyze Stark spectra of the OH–H2O and OH–D2O binary complexes, revealing a 3.70(5) D permanent electric dipole moment. Computations of the dipole moment are in good agreement with experiment when large-amplitude vibrational averaging is taken into account. Polarization spectroscopy is employed to characterize two vibrational bands assigned to OH(D2O)2, revealing two nearly isoenergetic cyclic isomers that differ in the orientation of the non-hydrogen-bonded deuterium atoms relative to the plane of the three oxygen atoms. The dipole moments for these clusters are determined to be approximately 2.5 and 1.8 D for “up-up” and “up-down” structures, respectively. Hydroxyl stretching bands of larger clusters containing three or more D2O molecules are observed shifted approximately 300 cm−1 to the red of the isolated OH radical. Pressure dependence studies and ab initio calculations imply the presence of multiple cyclic isomers of OH(D2O)3.Fil: Hernández, Federico Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; Argentina. University of Georgia; Estados UnidosFil: Brice, Joseph T.. University of Georgia; Estados UnidosFil: Leavitt, Christopher M.. University of Georgia; Estados UnidosFil: Liang, Tao. University of Georgia; Estados UnidosFil: Raston, Paul L.. James Madison University. Department of Chemistry and Biochemistry; Estados UnidosFil: Pino, Gustavo Ariel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Douberly, Gary E.. University of Georgia; Estados Unido

Paclitaxel-loaded phosphonated calixarene nanovesicles as a modular drug delivery platform

This work is licensed under a Creative Commons Attribution 4.0 International License. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder to reproduce the material. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/A modular p-phosphonated calix[4]arene vesicle (PCV) loaded with paclitaxel (PTX) and conjugated with folic acid as a cancer targeting ligand has been prepared using a thin film-sonication method. It has a pH-responsive capacity to trigger the release of the encapsulated PTX payload under mildly acidic conditions. PTX-loaded PCV conjugated with alkyne-modified PEG-folic acid ligands prepared via click ligation (fP-PCVPTX) has enhanced potency against folate receptor (FR)-positive SKOV-3 ovarian tumour cells over FR-negative A549 lung tumour cells. Moreover, fP-PCVPTX is also four times more potent than the non-targeting PCVPTX platform towards SKOV-3 cells. Overall, as a delivery platform the PCVs have the potential to enhance efficacy of anticancer drugs by targeting a chemotherapeutic payload specifically to tumours and triggering the release of the encapsulated drug in the vicinity of cancer cells

Poly[[(acetonitrile)­lithium(I)]-μ3-tetra­fluoridoborato]

The structure of the title compound, [Li(BF4)(CH3CN)]n, consists of a layered arrangement parallel to (100) in which the Li+ cations are coordinated by three F atoms from three tetra­fluoridoborate (BF4 −) anions and an N atom from an acetonitrile mol­ecule. The BF4 − anion is coordinated to three different Li+ cations though three F atoms. The structure can be described as being built from vertex-shared BF4 and LiF3(NCCH3) tetra­hedra. These tetra­hedra reside around a crystallographic inversion center and form 8-membered rings

Poly[bis­(acetonitrile-κN)bis­[μ3-bis(tri­fluoro­methane­sulfonyl)­imido-κ4 O,O′:O′′:O′′′]dilithium]

In the title compound, [Li2(CF3SO2NSO2CF3)2(CH3CN)2]n, two Li+ cations reside on crystallographic inversion centers, each coordinated by six O atoms from bis(trifluoromethanesulfonyl)imide (TFSI−) anions. The third Li+ cation on a general position is four-coordinated by two anion O atoms and two N atoms from acetonitrile mol­ecules in a tetra­hedral geometry

INFRARED AND MICROWAVE-INFRARED DOUBLE RESONANCE SPECTROSCOPY OF METHANOL EMBEDDED IN SUPERFLUID HELIUM NANODROPLETS

Author Institution: Department of Chemistry, University of Alberta, Edmonton, Alberta T6G-2G2, CanadaMethanol is one of the simplest torsional oscillators, and has been extensively studied in the gas phase by various spectroscopic techniques. At 300 K, a large number of rotational, torsional, and vibrational energy levels are populated, and this makes for a rather complicated infrared spectrum which is still not fully understood. It is expected that in going from 300 K to 0.4 K (the temperature of helium nanodroplets) that the population distribution of methanol will collapse into one of two states; the \textit{J,K} = 0,0 level for the \textit{A} symmetry species, and the \textit{J,K} = 1,-1 level for the \textit{E} symmetry species. This results in a simplified spectrum that consists of narrow \textit{a}-type lines and broader \textit{b}-type lines in the OH stretching region. Microwave-infrared double resonance spectroscopy is used to help assign the \textit{a}-type infrared lines