Analogous to cellulose, polymers whose monomer units possess both hydrogen donators and acceptors are generally insoluble in ambient water because of hydrogen bonding (HB). Herein we present stimuli-responsive long aqueous cylindrical vesicles (nanotubes) synthesized directly using HB-driven polymerization-induced self-assembly (PISA) under visible-light-mediated RAFT aqueous dispersion polymerization at 25 °C. The PISA undergoes an unprecedented film/silk-to-ribbon-to-vesicle transition and films/silks/ribbons formed at low DPs (∼25–85) of core-forming block in free-flowing aqueous solution. Pore-switchable nanotubes are synthesized by electrostatic repulsive perturbation of the HB association in anisotropic vesicular membranes via inserting minor ionized monomer units into the core-forming block. These nanotubes are synthesized at >35% solids, and tubular membranes are more sensitive than spherical counterparts in response to aqueous surroundings. This facile, robust, and general strategy paves a new av...

Synthesis of Hydrogen-Bonded Pore-Switchable Cylindrical Vesicles via Visible-Light-Mediated RAFT Room-Temperature Aqueous Dispersion Polymerization

Binding energy of van der Waals- and hydrogen-bonded clusters by threshold ionization techniques

Molecular phonon couplers at carbon nanotube/substrate interface to enhance interfacial thermal transport

2 Matrix isolation

The infrared absorption spectra of acetone and methanol mixtures have been investigated in a solid argon matrix at 9 K. A number of intramolecular complex bands were observed both in the acetone and methanol fundamental regions. From the concentration dependence of the infrared spectral pattern, acetone and methanol seemed to form a 1:1 binary complex. Noticeable red-shifts of the CO stretching mode of acetone as well as the OH stretching mode of methanol suggest that the two molecules are bound mainly through a H-bond between the carbonyl oxygen and the hydroxyl hydrogen atoms. A relatively weaker H-bonded interaction appeared also to act between the oxygen atom of methanol and a hydrogen atom of acetone. This view was found to be consistent with ab initio SCF, MP2, and DFT level computations. The most stable structure calculated was found to possess those two kinds of H-bonds, assuming a planar six-membered ring-like structure.

Infrared matrix isolation study of acetone and methanol in solid argon

Gas phase hydrogen bonding was studied via infrared spectroscopy in the following systems:  methyl acetate−hydrogen chloride, methyl formate−hydrogen chloride, 2-butanone−hydrogen chloride, and acetone−hydrogen chloride. The intensity of the H−Cl stretching vibration was monitored as a function of temperature, and the hydrogen bond energies and enthalpies were determined. The hydrogen bond energy for all four complexes was within 2.0 kJ mol-1 of −18.3 kJ mol-1, indicating that the hydrogen bond energy is only minimally affected by nonlocal molecular structure. The acetone−hydrogen chloride complex was modeled by ab initio methods. The energy of formation of the complex, calculated at the MP2/6-311++G** level of theory, is −20.8 kJ mol-1, in good agreement with the experiment.

Hydrogen Bond Energies of Hydrogen Chloride−Carbonyl Complexes

Infrared Spectroscopic Study of the Cryogenic Thin Film and Matrix-Isolated Complexes of TiCl4 with NH3 and (CH3)3N

Infrared Spectroscopic Study of the Matrix-Isolated Complexes of TiCl(4) with PH(3) and AsH(3).

The initial steps of the reaction of TiCl4 with CH3OH and its isotopomers have been investigated using matrix isolation with infrared spectroscopic detection of the reaction intermediates. When twin jet deposition was employed, a substantial yield of a 1:1 adduct was observed. However, when merged jet deposition was employed with a 15 cm merged reaction region, no traces of the precursors or the 1:1 complex were observed. Rather, very intense bands due to previously unreported monomeric Cl3TiOCH3 were observed, as well as bands due to HCl. Band assignments were assisted by extensive isotopic labeling and supported by density functional calculations. In subsequent experiments, heating the merged region to as high as 350 °C led to complete destruction of the bands to Cl3TiOCH3 while bands due to CH3Cl and the complex of CH3Cl with HCl were observed to grow.

Jennifer B. Everhart

Papers

Hydrogen Bond Energies of Hydrogen Chloride−Carbonyl Complexes

Infrared Spectroscopic Study of the Cryogenic Thin Film and Matrix-Isolated Complexes of TiCl4 with NH3 and (CH3)3N

Infrared Spectroscopic Study of the Matrix-Isolated Complexes of TiCl(4) with PH(3) and AsH(3).

Matrix Isolation Study of the Reaction of TiCl4 with CH3OH: Synthesis and Characterization of Cl3TiOCH3