80
P. Panwaria and A. Das
Fig. 11 A A representative example of single water-mediated selenium hydrogen bonding interaction between the indole moiety of the tryptophan and selenomethionine residues in the PDB:
3D5P; B Mass-selected IR spectra of (a) indole and (c) indole…H 2 O…Me 2 Se complexes. Theoretical IR spectra of the (b) indole monomer and (d) indole…H 2 O…Me 2 Se complex calculated at
the ωB97X-D/6–311++G(d,p) level of theory Adapted with permission from Ref. [193], copyright
2019, American Chemical Society)
4 Conclusions and Future Outlook
In this chapter, we have provided a brief overview of jet-cooled laser spectroscopic
techniques with resonantly enhanced multiphoton ionization (REMPI) time of flight
mass spectrometry as well as fluorescence detection scheme. Jet-cooled spectroscopy
is unique in rendering high resolution electronic and vibrational spectroscopy of
molecules and weakly bound complexes in an isolated gas phase. Intrinsic physical
properties of the molecular systems can be retrieved only from the data obtained from
isolated gas-phase spectroscopy as it is performed in the absence of any perturbation from any solvent as well as intermolecular interactions. Moreover, the isolated
gas-phase spectroscopy data are immensely valuable to benchmark various levels of
theories employed for quantum chemistry calculations. Here intrinsic nature, physical origin, and optimum strength of different non-covalent interactions, as well as the
subtle interplay between those interactions, have been explored by studying various
model complexes of biological relevance in the gas phase. The inherent existence
of various unconventional non-covalent interactions present in proteins and other
supramolecular assemblies can only be validated by studying those interactions in
the supersonic jet where additional interactions from surroundings or media are
entirely absent.
Gas-phase laser spectroscopy coupled with laser vaporization/desorption technique enables us to study non-volatile larger molecular systems such as peptides and
P. Panwaria and A. Das
Fig. 11 A A representative example of single water-mediated selenium hydrogen bonding interaction between the indole moiety of the tryptophan and selenomethionine residues in the PDB:
3D5P; B Mass-selected IR spectra of (a) indole and (c) indole…H 2 O…Me 2 Se complexes. Theoretical IR spectra of the (b) indole monomer and (d) indole…H 2 O…Me 2 Se complex calculated at
the ωB97X-D/6–311++G(d,p) level of theory Adapted with permission from Ref. [193], copyright
2019, American Chemical Society)
4 Conclusions and Future Outlook
In this chapter, we have provided a brief overview of jet-cooled laser spectroscopic
techniques with resonantly enhanced multiphoton ionization (REMPI) time of flight
mass spectrometry as well as fluorescence detection scheme. Jet-cooled spectroscopy
is unique in rendering high resolution electronic and vibrational spectroscopy of
molecules and weakly bound complexes in an isolated gas phase. Intrinsic physical
properties of the molecular systems can be retrieved only from the data obtained from
isolated gas-phase spectroscopy as it is performed in the absence of any perturbation from any solvent as well as intermolecular interactions. Moreover, the isolated
gas-phase spectroscopy data are immensely valuable to benchmark various levels of
theories employed for quantum chemistry calculations. Here intrinsic nature, physical origin, and optimum strength of different non-covalent interactions, as well as the
subtle interplay between those interactions, have been explored by studying various
model complexes of biological relevance in the gas phase. The inherent existence
of various unconventional non-covalent interactions present in proteins and other
supramolecular assemblies can only be validated by studying those interactions in
the supersonic jet where additional interactions from surroundings or media are
entirely absent.
Gas-phase laser spectroscopy coupled with laser vaporization/desorption technique enables us to study non-volatile larger molecular systems such as peptides and