Hydrogen-Bonded Complexes of Phenylacetylene with Water, Methanol, Ammonia, and Methylamine. The Origin of Methyl Group-Induced Hydrogen Bond Switching

Sedlák, Róbert; Hobza, Pavel; Patwari, G. Naresh

doi:10.1021/jp900813n

Cited by 38 publications

(52 citation statements)

References 26 publications

(51 reference statements)

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“…, respectively, over the formation of PW1 and PW2 at 10 K. [33] The vibrational spectra and the energetics support the assignment of PW3 as the structure observed in the gas phase. It is interesting to note that the structure of the phenylacetylene-water complex is different from both benzene-water and acetylene-water complexes, [57][58][59][60][61] even though the phenylacetylene incorporates both the features of benzene and acetylene.…”

supporting

confidence: 59%

“…Based on the FDIR spectrum (Figure 17 A) the formation of a CÀH···N hydrogen-bonded complex can be ruled out completely, as this complex would have a much lower acetylenic CÀH stretching frequency than complexes with ammonia and methylamine. [32,33,37] Further, the appearance of the Fermi resonance bands is also an indication that the acetylenic group of phenylacetylene is relatively unperturbed upon interaction with 1,3,5-triazine. In the case of phenylacetylene complexes with water, methylamine, and trifluoroethanol, we showed that the interaction of the solvent molecule with the p-electron density of the acetylenic CC bond leads to loss of Fermi mixing.…”

Section: The 135-triazine Complexmentioning

confidence: 99%

“…The shift in the electronic transition and the IR spectrum in the aromatic CÀH stretching region indicate that PMA4 yields the IDIR spectrum depicted in Figure 8 B. [32,33,37] On the other hand, the structure PMA1 can be straightforwardly assigned to the IDIR spectrum in Figure 8 C. It incorporates the formation of a CÀH···N hydrogen bond similar to that of the ammonia complex. Additionally, the shift in the acetylenic CÀH stretching frequency for the methylamine complex (139 cm À1 ) is higher than for the ammonia complex (103 cm…”

mentioning

confidence: 91%

“…The stabilization energies and the free energy of formation at 10 K calculated at the CCSD(T)/aug-cc-pVDZ//MP2/aug-cc-pVDZ level of theory show that PM2 is the most stable structure (see Table 1). [33] The FDIR spectra in both the acetylenic CÀH and the OÀH stretching regions can only be explained on the basis of structure PM2, which also is the global minimum for the phenylacetylene-methanol complex.…”

mentioning

confidence: 99%

“…The formation of PMA4 was attributed to kinetic trapping or higher accessibility. [33,37] One of the most interesting features of methylamine complexes is the isomer-dependent fluorescence properties. The LIF excitation spectrum of phenylacetylene in the presence of methylamine is depicted in Figure 10 tum yield for the M 2 complex is much lower than the detection threshold of our apparatus.…”

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confidence: 99%

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Phenylacetylene: A Hydrogen Bonding Chameleon

et al. 2010

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Molecules with multiple hydrogen bonding sites offer the opportunity to investigate competitive hydrogen bonding. Such an investigation can become quite interesting, particularly when the molecule of interest has neither lone-pair electrons nor strongly acidic/basic groups. Phenylacetylene is one such molecule with three hydrogen bonding sites that cannot be ranked into any known hierarchical pattern. Herein we review the structures of several binary complexes of phenylacetylene investigated using infrared optical double-resonance spectroscopy in combination with high-level ab initio methods. The diversity of intermolecular structures formed by phenylacetylene with various reagents is remarkable. The nature of intermolecular interaction with various reagents is the result of a subtle balance between various configurations and competition between the electrostatic and dispersion energy terms, while trying to maximize the total interaction strength.

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confidence: 59%

Section: The 135-triazine Complexmentioning

confidence: 99%

mentioning

confidence: 91%

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confidence: 99%

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confidence: 99%

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Phenylacetylene: A Hydrogen Bonding Chameleon

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Binary Complexes of Ammonia with Phenylacetylenes: A Combined Experimental and Computational Approach to Explore Multiple Minima on Intermolecular Potentials

2012

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The hydrogen-bonded complexes of phenylacetylene, 4-fluorophenylacetylene, 2-fluorophenylacetylene, and 2,6-difluorophenylacetylene with ammonia are investigated using IR-UV double resonance spectroscopy in combination with high-level ab initio calculations at the CCSD(T)/CBS level of theory. The C-H···N hydrogen-bonded complex, which involves an interaction of ammonia with the acetylenic CH group is the global minimum and is observed in all four cases investigated. In addition, phenylacetylene and 4-fluorophenylacetylene form a quasi-planar cyclic complexes with ammonia incorporating N-H···π and C-H···N hydrogen bonds, wherein the π-electron density of the acetylenic C≡C bond acts as an acceptor to the N-H group of ammonia. A third ammonia complex is observed for 4-fluorophenylacetylene in which ammonia interacts with the fluorine atom once again, leading to the formation of a quasi-planar cyclic complex. The substitution of the fluorine atom on the phenyl ring of phenylacetylene modulates the intermolecular potentials, which are dependent on the position of the substitution.

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Molecular structure of trimethyl[(3-indole)ethoxy]silane cooled in a supersonic jet

et al. 2010

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UDC 535.37Conformations of He-jet-cooled trimethyl [(3-indole)ethoxy]silane (TIES) have been studied using a laser spectroscopy technique in combination with quantum-chemical computations. Six probable conformers of the molecule were computed, of which only two conformations were observed. Based on an analysis of fluorescence excitation spectra, fluorescence spectra, shapes of rotational band contours at the electronic S 0 -S 1 transition of TIES, and theoretical computations, the above conformers were assigned to steric structures. Twisted structures have the lowest energy due to intramolecular hydrogen bonds C-H⋅⋅⋅O< C Si between hydrogen atoms of methyl groups and an oxygen atom and C-H⋅⋅⋅π between H and the π-electron cloud of the indole ring.Introduction. The non-classical hydrogen bond, interaction between an H atom (bound to one of the electronegative C, O, or N atoms) and the π-electron cloud of an aromatic ring, has been widely studied in the last decade. Such weak non-covalent bonds are formed intramolecularly [1-3] or intermolecularly [4,5] in van-der-Waals complexes in biological systems. Weak H-bonds should be considered when examining molecular structures of fluxional molecules and their stabilization energies. Frequencies of purely electronic S 0 -S 1 -transitions of organic molecular structures vary from units to tens of inverse centimeters [1][2][3]. This makes it possible to use jet cooling to identify these conformers. Various methods of laser UV and IR spectroscopy are used in such investigations. The preferred structures can be determined when they are combined with modern quantum-chemical computation methods.Herein we analyze the molecular structures of trimethyl[(3-indole)ethoxy]silane (TIES) and examine the effect of an intramolecular H-bond on the stabilization energy of its conformers.Experimental. Fluorescence excitation and fluorescence spectra were measured using the automated spectrometry complex that was described before [6]. The carrier gas, He at a pressure of 2 atm, was fed into a prechamber heated to 400 K that contained saturated TIES vapor. The liquid organic compound was placed into capillaries (0.75 internal diameter, 30 mm long). The number of capillaries was selected so that the optimal luminescence signal was obtained. A pulsed supersonic stream was formed by flowing the gas mixture into the vacuum chamber through a round nozzle (diameter 0.7 mm). The cooled molecules were excited by the second harmonic of a frequency-tuned dye laser at distances of 19 and 10 mm from the nozzle for recording fluorescence excitation and fluorescence spectra, respectively. The dye laser was pumped by the second harmonic of a Nd-doped yttrium-aluminum garnet laser (LOTIS TII, LS-2134). The wavelengths of the first harmonic of the dye laser were calibrated using the fluorescence excitation spectrum of iodine vapor. Integral fluorescence was recorded using a Hamamatsu R928 photoelectron multiplier. A DFS-52 monochromator with a diffraction grating (2400 lines/mm) was used to study the fluores...

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Hydrogen-Bonded Complexes of Phenylacetylene with Water, Methanol, Ammonia, and Methylamine. The Origin of Methyl Group-Induced Hydrogen Bond Switching

Cited by 38 publications

References 26 publications

Phenylacetylene: A Hydrogen Bonding Chameleon

Phenylacetylene: A Hydrogen Bonding Chameleon

Binary Complexes of Ammonia with Phenylacetylenes: A Combined Experimental and Computational Approach to Explore Multiple Minima on Intermolecular Potentials

Molecular structure of trimethyl[(3-indole)ethoxy]silane cooled in a supersonic jet

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