In this article, the new and exciting techniques of infrared consequence spectroscopy (sometimes called action spectroscopy) of gaseous ions are reviewed. These techniques include vibrational predissociation spectroscopy and infrared multiple photon dissociation spectroscopy and they typically complement one another in the systems studied and the information gained. In recent years infrared consequence spectroscopy has provided long-awaited direct evidence into the structures of gaseous ions from organometallic species to strong ionic hydrogen bonded structures to large biomolecules. Much is being learned with respect to the structures of ions without their stabilizing solvent which can be used to better understand the effect of solvent on their structures. This review mainly covers the topics with which the author has been directly involved in research: structures of proton-bound dimers, protonated amino acids and DNA bases, amino acid and DNA bases bound to metal ions and, more recently, solvated ionic complexes. It is hoped that this review reveals the impact that infrared consequence spectroscopy has had on the field of gaseous ion chemistry.

Infrared consequence spectroscopy of gaseous protonated and metal ion cationized complexes

Ammonia (NH3) is an irritant gas with a unique pungent odor; sub-parts per million-level breath ammonia is a medical biomarker for kidney disorders and Helicobacter pylori bacteria-induced stomach ...

Flexible Room-Temperature NH3 Sensor for Ultrasensitive, Selective, and Humidity-Independent Gas Detection.

Ensemble infrared photodissociation (IRPD) spectra in the hydrogen stretch region (∼2800–3800 cm–1) are reported for aqueous nanodrops containing ∼250 water molecules and either SO42–, I–, Na+, Ca2+, or La3+ at 133 K. Each spectrum has a broad feature in the bonded-OH region (∼2800–3500 cm–1) and a sharp feature near 3700 cm–1, corresponding to the free-OH stretch of surface water molecules that accept two hydrogen bonds and donate one hydrogen bond (AAD water molecules). A much weaker band corresponding to AD surface water molecules is observed for all ions except SO42–. The frequencies of the AAD free-OH stretch red-shift with increasingly positive charge, consistent with a Stark effect as a result of the ion’s electric field at the droplet surface, and from which the corresponding frequency for water molecules at the surface of neutral nanodrops of this size is estimated to be 3699.3–3700.1 cm–1. The intensity of the AAD band increases with increasing positive charge, consistent with a greater populati...

Effects of Ions on Hydrogen-Bonding Water Networks in Large Aqueous Nanodrops

Beginning in the mid-1980s, a number of innovative experimental studies on ionic clusters emerged from the laboratory of Yuan T. Lee combining infrared laser spectroscopy and tandem mass spectrometry. Coupled with modern electronic structure calculations, this research explored many facets of ionic clusters including solvation, structure, and dynamics. These efforts spawned a resurgence in gas-phase cluster spectroscopy. This paper will focus on the major areas of research initiated by the Lee group and how these studies stimulated and influenced others in what is currently a vibrant and growing field.

Infrared studies of ionic clusters: the influence of Yuan T. Lee.

Ionophore-doped sensing membranes exhibit greater selectivities and wider measuring ranges if their membrane matrixes are noncoordinating and solvate interfering ions poorly. This is particularly true for fluorous phases, which are the least polar and polarizable condensed phases known. In this work, fluorous membrane matrixes were used to prepare silver ion-selective electrodes (ISEs). Sensing membranes composed of perfluoroperhydrophenanthrene, sodium tetrakis[3,5-bis(perfluorohexyl)phenyl]borate, and one of four fluorophilic Ag+-selective ionophores with one or two thioether groups were investigated. All electrodes exhibited Nernstian responses to Ag+ in a wide range of concentrations. Their selectivities for Ag+ over interfering ions were found to depend on host preorganization and the length of the −(CH2)n− spacers separating the coordinating thioether group from the strongly electron withdrawing perfluoroalkyl groups. ISEs based on the most selective of the four ionophores, that is, 1,3-bis(perfluor...

Highly Selective Detection of Silver in the Low ppt Range with Ion-Selective Electrodes Based on Ionophore-Doped Fluorous Membranes

M(+)(H(2)O)(n) and M(+)(H(2)O)(n)Ar ions (M=Cu and Ag) are studied for exploring coordination and solvation structures of noble-metal ions These species are produced in a laser-vaporization cluster source and probed with infrared (IR) photodissociation spectroscopy in the OH-stretch region using a triple quadrupole mass spectrometer Density functional theory calculations are also carried out for analyzing the experimental IR spectra Partially resolved rotational structure observed in the spectrum of Ag(+)(H(2)O)(1) x Ar indicates that the complex is quasilinear in an Ar-Ag(+)-O configuration with the H atoms symmetrically displaced off axis The spectra of the Ar-tagged M(+)(H(2)O)(2) are consistent with twofold coordination with a linear O-M(+)-O arrangement for these ions, which is stabilized by the s-d hybridization in M(+) Hydrogen bonding between H(2)O molecules is absent in Ag(+)(H(2)O)(3) x Ar but detected in Cu(+)(H(2)O)(3) x Ar through characteristic changes in the position and intensity of the OH-stretch transitions The third H(2)O attaches directly to Ag(+) in a tricoordinated form, while it occupies a hydrogen-bonding site in the second shell of the dicoordinated Cu(+) The preference of the tricoordination is attributable to the inefficient 5s-4d hybridization in Ag(+), in contrast to the extensive 4s-3d hybridization in Cu(+) which retains the dicoordination This is most likely because the s-d energy gap of Ag(+) is much larger than that of Cu(+) The fourth H(2)O occupies the second shells of the tricoordinated Ag(+) and the dicoordinated Cu(+), as extensive hydrogen bonding is observed in M(+)(H(2)O)(4) x Ar Interestingly, the Ag(+)(H(2)O)(4) x Ar ions adopt not only the tricoordinated form but also the dicoordinated forms, which are absent in Ag(+)(H(2)O)(3) x Ar but revived at n=4 Size dependent variations in the spectra of Cu(+)(H(2)O)(n) for n=5-7 provide evidence for the completion of the second shell at n=6, where the dicoordinated Cu(+)(H(2)O)(2) subunit is surrounded by four H(2)O molecules The gas-phase coordination number of Cu(+) is 2 and the resulting linearly coordinated structure acts as the core of further solvation processes

Infrared spectroscopy of Cu+(H2O)(n) and Ag+(H2O)(n): coordination and solvation of noble-metal ions.

https://ir.lib.hiroshima-u.ac.jp/files/public/3/38236/20151007111527138064/ChemPhysLett_2006_427_24.pdf

Infrared photodissociation spectra and solvation structures of Mg+(CH3OH)n (n=1–4)

Vibrational spectra of mass-selected Ag+(H2O)n ions are measured by infrared photodissociation spectroscopy and analyzed with the aid of density functional theory calculations. Hydrogen bonding between H2O molecules is found to be absent for cold Ag+(H2O)3, but detected for Ag+(H2O)4 through characteristic changes in the position and intensity of OH-stretching transitions. The third H2O coordinates directly to Ag+, but the fourth H2O prefers solvation through hydrogen bonding. The preference of the tri-coordinated form is attributed to the inefficient 5s–4d hybridization in Ag+, in contrast to the efficient 4s–3d hybridization in Cu+. For Ag+(H2O)4, however, di-coordinated isomers are identified in addition to the tri-coordinated one.

Coordination and solvation of noble metal ions: Infrared spectroscopy of Ag+(H2O)n

Coordination and solvation structures of the Cu+(NH3)n ions with n = 3–8 are studied by infrared photodissociation spectroscopy in the NH-stretch region with the aid of density functional theory calculations. Hydrogen bonding between NH3 molecules is absent for n = 3, indicating that all NH3 molecules are bonded directly to Cu+ in a tri-coordinated form. The first sign of hydrogen bonding is detected at n = 4 through frequency reduction and intensity enhancement of the infrared transitions, implying that at least one NH3 molecule is placed in the second solvation shell. The spectra of n = 4 and 5 suggest the coexistence of multiple isomers, which have different coordination numbers (2, 3, and 4) or different types of hydrogen-bonding configurations. With increasing n, however, the di-coordinated isomer is of growing importance until becoming predominant at n = 8. These results signify a strong tendency of Cu+ to adopt the twofold linear coordination, as in the case of Cu+(H2O)n.

Coordination and solvation of copper ion: infrared photodissociation spectroscopy of Cu+(NH3)n (n = 3–8)

https://ir.lib.hiroshima-u.ac.jp/files/public/3/38232/20151006141541724065/ChemPhysLett_2006_419_201.pdf

Takuro Iino

Papers

Infrared spectroscopy of Cu+(H2O)(n) and Ag+(H2O)(n): coordination and solvation of noble-metal ions.

Infrared photodissociation spectra and solvation structures of Mg+(CH3OH)n (n=1–4)

Coordination and solvation of noble metal ions: Infrared spectroscopy of Ag+(H2O)n

Coordination and solvation of copper ion: infrared photodissociation spectroscopy of Cu+(NH3)n (n = 3–8)

Infrared photodissociation spectroscopy of [Al(NH3)n]+ (n = 1-5) : solvation structures and insertion reactions of Al+ into NH3