Chirality Effects on the IRMPD Spectra of Basket Resorcinarene/Nucleoside Complexes

Abstract

The IRMPD spectra of the ESI‐formed proton‐bound complexes of the R,R,R,R‐ and S,S,S,S‐enantiomers of a bis(diamido)‐bridged basket resorcin[4]arene (R and S) with cytosine (1), cytidine (2), and cytarabine (3) were measured in the region 2800–3600 cm−1. Comparison of the IRMPD spectra with the corresponding ONIOM (B3LYP/6‐31(d):UFF)‐calculated absorption frequencies allowed the assessment of the vibrational modes that are responsible for the observed spectroscopic features. All of the complexes investigated, apart from [R⋅H⋅3]+, showed similar IRMPD spectra, which points to similar structural and conformational landscapes. Their IRMPD spectra agree with the formation of several isomeric structures in the ESI source, wherein the N(3)‐protonated guest establishes noncovalent interactions with the host amidocarbonyl groups that are either oriented inside the host cavity or outside it between one of the bridged side‐chains and the upper aromatic nucleus. The IRMPD spectrum of the [R⋅H⋅3]+ complex was clearly different from the others. This difference is attributed to the effect of intramolecular hydrogen‐bonding interactions between the C(2′)OH group and the aglycone oxygen atom of the nucleosidic guest upon repulsive interactions between the same oxygen atom and the aromatic rings of the host.

Cisplatin Primary Complex with l‐Histidine Target Revealed by IR Multiple Photon Dissociation (IRMPD) Spectroscopy

“…Structural characterization of what appears to be a mixture of isomers has been sought based on the diagnostic power of IR spectroscopy of sampled gaseous ions as obtained by IRMPD spectroscopy supported by quantum chemical calculations . Therefore, cis ‐[PtCl(NH 3 ) 2 (His)] + ions are examined by IRMPD spectroscopy in two spectral ranges, namely 900–1900 cm −1 and 3000–3700 cm −1 , by using the CLIO FEL and a tabletop OPO/OPA laser system as IR light sources, respectively . The analysis of IRMPD spectra is aided by a comprehensive computational survey of the potential structures accounting for the sampled species and their respective calculated IR spectra.…”

Stereochemical Preference of 2'‐Deoxycytidine for Chiral Bis(diamido)‐bridged Basket Resorcin[4]arenes

“…Interestingly, proton‐bound diastereomeric complexes of the above mentioned hosts with pyrimidine nucleosides behave as supramolecular “chiroselective logic gates” in the gas phase by releasing the nucleoside depending on the resorcin[4]arene configuration . This interesting property has been demonstrated by mass spectrometry, and, more recently, by variable‐wavelength infrared multiple photon dissociation (IRMPD), allowing differentiation of the complexes formed in the gas phase by (all-S)-1 and (all-R)-1 and selected nucleosides. The lattened cone conformation was assumed as ground state stereochemistry of the resorcinarene.…”

Chirality effects in gas-phase spectroscopy and photophysics of molecular and ionic complexes: contribution of low and room temperature studies

“…MS approaches of chiral recognition have been the subject of several review articles [35,[47][48][49]. However, studies of chiral recognition coupling spectroscopy and MS are still scarce [22,50,51] and this review will focus on them as well as on the photophysical properties of the studied systems. Low temperature as achieved in supersonic expansions and room-temperature experiments, in ion trap or in the bulk, give complementary information.…”