Nitrosyl-heme and anion-arene complexes: structure, reactivity and spectroscopy

Two topics are selected and illustrated to exemplify (i) a biological and (ii) an organic ionic intermediate. The reactivity behavior of NO adducts with ferric and ferrous hemes has shown remarkable similarities when examined in the gas phase, demonstrating that the largely different NO affinity displayed in solution and in biological media is due to the different coordination environment. In fact, ferrous hemes present a vacant or highly labile axial coordination site, prone to readily bind NO. The vibrational signatures of the NO ligand have also been probed in vacuo for the first time in the nitrosyl complexes deriving from ferrous and ferric hemes under strictly comparable five-coordination at the metal center. Negatively charged sigma-adducts, from the association of anions with 1,3,5-trinitrobenzene, an exemplary pi-electron-deficient arene, have been probed by IRMPD spectroscopy and found to display variable binding motifs from a strongly covalent sigma-adduct (Meisenheimer complex) to a weakly covalent sigma-complex, depending on the anion basicity

Vibrational signatures of gaseous Meisenheimer complexes bonded at carbon and nitrogen

Anionic adducts of 1,3,5-trinitrobenzene (TNB) with deprotonated pyrrolidine (Pyr), imidazole (Im), acetone (Ac) and acetylacetone (Acac) have been delivered into the gas phase by electrospray ionization.The so-formed ions, TNB-Nu−(Nu = Pyr, Im, Ac, Acac), have been interrogated by IRMPD spectroscopy inthe fingerprint range. DFT calculations at B3LYP/6-311++G(d,p) level have been performed for a survey of candidate structures. All adducts conform to anionic sigma-complexes (Meisenheimer complexes). The symmetric stretching modes of the nitro groups yield a dominant vibrational signature at 1200–1250 cm−1,the red-shift with respect to the degenerate frequency of 1367 cm−1 in neutral TNB reflecting the extent of negative charge delocalization. The enol complexes TNB-Ac− and TNB-Acac− are largely representedby C-bonded species

Complexation of halide ions to tyrosine: role of non-covalent interactions evidenced by IRMPD spectroscopy

The binding motifs in the halide adducts with tyrosine ([Tyr + X]-, X = Cl, Br, I) have been investigated and compared with the analogues with 3-nitrotyrosine (nitroTyr), a biomarker of protein nitration, in a solvent-free environment by mass-selected infrared multiple photon dissociation (IRMPD) spectroscopy over two IR frequency ranges, namely 950–1950 and 2800–3700 cm-1. Extensive quantum chemical calculations at B3LYP, B3LYP-D3 and MP2 levels of theory have been performed using the 6-311++G(d,p) basis set to determine the geometry, relative energy and vibrational properties of likely isomers and interpret the measured spectra. A diagnostic carbonyl stretching band at B1720 cm-1 from the intact carboxylic group characterizes the IRMPD spectra of both [Tyr + X]- and [nitroTyr + X]-, revealing that the canonical isomers (maintaining intact amino and carboxylic functions) are the prevalent structures. The spectroscopic evidence reveals the presence of multiple non-covalent forms. The halide complexes of tyrosine conform to a mixture of plane and phenol isomers. The contribution of phenol-bound isomers is sensitive to anion size, increasing from chloride to iodide, consistent with the decreasing basicity of the halide, with relative amounts depending on the relative energies of the respective structures. The stability of the most favorable phenol isomer with respect to the reference plane geometry is in fact 1.3, -2.1, -6.8 kJ mol-1, for X = Cl, Br, I, respectively. The change in p-acidity by ring nitration also stabilizes anion–p interactions yielding ring isomers for [nitroTyr + X]-, where the anion is placed above the face of the aromatic ring

Differences in Perceived and Experienced Stigma Between Problematic Gamblers and Non-gamblers in a General Population Survey

We consider a sample of about 700 people, interviewed on the streets, who are sorted into two groups by a self-report, screening questionnaire: namely, non-problematic gamblers/non-gamblers and problematic gamblers. Within each group, we compare both social (perceived) stigma and self-perceived (experienced) stigma, measured by means of other two self-report questionnaires, and we seek for relations between stigma and socio-demographic variables that can help targeting possible interventions to reduce gambling-related stigma. We, then, compare stigma between the two groups of non-(problematic) gamblers and problematic ones, and we also check the hypothesis that higher social stigma is related to higher self-perceived stigma, as well as higher stigma is related to lesser help-seeking. The latter hypothesis is of utmost importance, given that stigma is recognised to be one of the major causes for hindering help-seeking by problematic gamblers. The research is carried out in Italy, one of the first countries in the world for the money spent per capita in gambling activity every year

IR ion spectroscopy in a combined approach with MS/MS and IM-MS to discriminate epimeric anthocyanin glycosides (cyanidin 3-O-glucoside and -galactoside)

Anthocyanins are widespread in plants and flowers, being responsible for their different colouring. Two representative members of this family have been selected, cyanidin 3-O-β-glucopyranoside and 3-O-β-galactopyranoside, and probed by mass spectrometry based methods, testing their performance in discriminating between the two epimers. The native anthocyanins, delivered into the gas phase by electrospray ionization, display a comparable drift time in ion mobility mass spectrometry (IM-MS) and a common fragment, corresponding to loss of the sugar moiety, in their collision induced dissociation (CID) pattern. However, the IR multiple photon dissociation (IRMPD) spectra in the fingerprint range show a feature particularly evident in the case of the glucoside. This signature is used to identify the presence of cyanidin 3-O-β-glucopyranoside in a natural extract of pomegranate. In an effort to increase any differentiation between the two epimers, aluminum complexes were prepared and sampled for elemental composition by FT-ICR-MS. CID experiments now display an extensive fragmentation pattern, showing few product ions peculiar to each species. More noteworthy is the IRMPD behavior in the OH stretching range showing significant differences in the spectra of the two epimers. DFT calculations allow to interpret the observed distinct bands due to a varied network of hydrogen bonding and relative conformer stability

IR spectrum of the protonated neurotransmitter 2-phenylethylamine: dispersion and anharmonicity of the NH3+-pi interaction

Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.The structure and dynamics of the highly flexible side chain of (protonated) phenylethylamino neurotransmitters are essential for their function. The geometric, vibrational, and energetic properties of the protonated neutrotransmitter 2-phenylethylamine (H(+)PEA) are characterized in the N-H stretch range by infrared photodissociation (IRPD) spectroscopy of cold ions using rare gas tagging (Rg = Ne and Ar) and anharmonic calculations at the B3LYP-D3/(aug-)cc-pVTZ level including dispersion corrections. A single folded gauche conformer (G) protonated at the basic amino group and stabilized by an intramolecular NH+-pi interaction is observed. The dispersion-corrected density functional theory calculations reveal the important effects of dispersion on the cation-pi interaction and the large vibrational anharmonicity of the NH3+ group involved in the NH+-pi hydrogen bond. They allow for assigning overtone and combination bands and explain anomalous intensities observed in previous IR multiplephoton dissociation spectra. Comparison with neutral PEA reveals the large effects of protonation on the geometric and electronic structure.EC/FP7/600209/EU/International Post-Doc Initiative of the Technische Universität Berlin/IPOD

Eating disorders in young patients with neurofibromatosis type 1

Aim: We describe the association of neurofibromatosis type 1 (NF1) and feeding and eating disorders (FED) in five patients admitted to our third level centre for both FED and NF1. Methods: Case series of five adolescent females with NF1 treated for FED. Results: We collected data from five patients with NF1 aged between 14 and 22 years, all females. The onset of eating disorder symptoms occurred between 13 and 19 years of age and was characterised by food intake restriction, associated with physical hyperactivity in three out of five cases. One patient also reported self-injurious acts and episodic binges. Patients received diagnoses of anorexia nervosa (AN, n = 2), atypical AN (n = 1), bulimia nervosa (n = 1), unspecified feeding and eating disorder (n = 1). Conclusion: The current literature reports a single case of an adult with NF1 and comorbid AN, focusing on the dermatological features of NF1. Our article describes a case series of five patients in developmental age affected by NF1 and FED. Clinical and psychological features of NF1 may play a role in the pathogenesis of FED when these two conditions co-occur. The dermatological alterations of NF1 may contribute to body image distortion that characterises AN. Further research is required to systematically screen populations of patients with NF1 for the presence of FED

Are you approaching me? Motor execution influences perceived action orientation

Human observers are especially sensitive to the actions of conspecifics that match their own actions. This has been proposed to be critical for social interaction, providing the basis for empathy and joint action. However, the precise relation between observed and executed actions is still poorly understood. Do ongoing actions change the way observers perceive others' actions? To pursue this question, we exploited the bistability of depth-ambiguous point-light walkers, which can be perceived as facing towards the viewer or as facing away from the viewer. We demonstrate that point-light walkers are perceived more often as facing the viewer when the observer is walking on a treadmill compared to when the observer is performing an action that does not match the observed behavior (e.g., cycling). These findings suggest that motor processes influence the perceived orientation of observed actions: Acting observers tend to perceive similar actions by conspecifics as oriented towards themselves. We discuss these results in light of the possible mechanisms subtending action-induced modulation of perception