Influence of Donor-Acceptor Distance Variation on Photoinduced Electron and Proton Transfer in Rhenium(I)-Phenol Dyads

A homologous series of four molecules in which a phenol unit is linked covalently to a rhenium(I) tricarbonyl diimine photooxidant via a variable number of p-xylene spacers (n = 0–3) was synthesized and investigated. The species with a single p-xylene spacer was structurally characterized to get some benchmark distances. Photoexcitation of the metal complex in the shortest dyad (n = 0) triggers release of the phenolic proton to the acetonitrile/water solvent mixture; a H/D kinetic isotope effect (KIE) of 2.0 ± 0.4 is associated with this process. Thus, the shortest dyad basically acts like a photoacid. The next two longer dyads (n = 1, 2) exhibit intramolecular photoinduced phenol-to-rhenium electron transfer in the rate-determining excited-state deactivation step, and there is no significant KIE in this case. For the dyad with n = 1, transient absorption spectroscopy provided evidence for release of the phenolic proton to the solvent upon oxidation of the phenol by intramolecular photoinduced electron transfer. Subsequent thermal charge recombination is associated with a H/D KIE of 3.6 ± 0.4 and therefore is likely to involve proton motion in the rate-determining reaction step. Thus, some of the longer dyads (n = 1, 2) exhibit photoinduced proton-coupled electron transfer (PCET), albeit in a stepwise (electron transfer followed by proton transfer) rather than concerted manner. Our study demonstrates that electronically strongly coupled donor–acceptor systems may exhibit significantly different photoinduced PCET chemistry than electronically weakly coupled donor–bridge–acceptor molecules

Progettazione e realizzazione di un sistema di refertazione specialistico-ambulatoriale

Come per tutte le strutture che erogano servizi sanitari, lo scopo di un ospedale è quello di soddisfare il bisogno di cure degli assistiti, nel rispetto della loro persona, offrendo un servizio di qualità. Nel caso di strutture private o enti ecclesiastici, che non sono supportate da finanziamenti dello Stato, l’attività di assistenza è inoltre organizzata in maniera tale da ottimizzare i costi, cercare di rendere sempre più efficienti le risorse a disposizione e quindi ridurre gli sprechi. I sistemi informativi ospedalieri hanno certamente contribuito al supporto delle operazioni svolte nei percorsi assistenziali e della comunicazione di informazioni cliniche dei pazienti all'interno della struttura tra il personale sanitario. Attualmente anche il web può essere considerata una risorsa e come tale può essere sfruttata per migliorare il servizio offerto, creare valore per i pazienti e ridurre lo spreco di risorse. Proprio grazie a questa consapevolezza, l’Agenzia per l’Italia Digitale ha stabilito un piano di intervento per promuovere le tecnologie ICT a supporto della pubblica amministrazione, e quindi anche in ambito sanitario. Il lavoro di questa tesi è stato svolto, in convenzione con l’Università di Pisa, presso l'Ospedale Card. G. Panico di Tricase, un ente ecclesiastico classificato come Azienda Ospedaliera, desideroso di allinearsi agli obiettivi proposti da tali piani di intervento. La prima fase si è focalizzata su una panoramica delle azioni previste dall’AgID e sull’analisi del contatto aziendale e in particolare del SIO esistente a supporto dei processi nell’assistenza ai pazienti. Da tale analisi sono emerse delle criticità nella gestione attuale dei dati clinici ed è stato quindi proposto di intervenire realizzando un dossier sanitario digitale, prerogativa assoluta per contribuire a realizzare il Fascicolo Sanitario Elettronico. Dopo aver definito l’oggetto dell’intervento, si è passati ad una fase di analisi del contesto di lavoro, che ha incluso lo studio dei requisiti funzionali e non funzionali da soddisfare, delle risorse a disposizione, dei sistemi esistenti coi quali interagirà, degli standard internazionali usati in tale ambito, dei vincoli tecnici e giuridici, delle architetture impiegate in questo settore. Sulla base di tali analisi e ricerche, e considerate le esigenze aziendali esposte dalla Direzione Sanitaria e dal personale medico coinvolto, è stato possibile procedere alla progettazione dell’applicazione e del database a supporto; per poi completare il lavoro con lo sviluppo del progetto tramite strumenti validi e consolidati. Il frutto del lavoro di tesi è rappresentato da un'applicazione java enterprise, basata su web services, organizzata secondo il pattern architetturale MVVM col supporto del framework open-source ZK. Il lavoro svolto è strutturato in più capitoli, i quali ripercorrono le fasi di analisi, progettazione e sviluppo sopra descritte, e si conclude con alcune considerazioni finali su impieghi futuri e possibili estensioni dell'applicazione creata

Organotrifluoroborates as attractive self-assembling systems: the case of bifunctional dipotassium phenylene-1,4-bis(trifluoroborate)

A multitude of non-covalent interactions, investigated by X-ray crystallography and computational chemistry techniques, proved to be responsible of the spontaneous self-assembly of a bis(trifluoroborate) dipotassium salt

O-Verbrückte Angucyclinone, Verfahren zu ihrer Herstellung, sie enthaltende Arzneimittel und deren Verwendung

Es werden das verbrückte Angucyclinon Gephyromycin (1a) und Derivate dieser Verbindung nach der allgemeinen Formel 1 beschrieben sowie ein Verfahren zu ihrer Herstellung. Diese Substanzen erhöhen die intrazelluläre Calciumkonzentration in Neuronen. Weiterhin besitzen sie eine antibiotische Wirkung gegenüber Gram-positiven Bakterien

Coordination isomerism in pentamethylcyclopentadienyl-substituted iminophosphanes: from classical structures to a π-complexed iminophosphenium ion

Novel iminophosphanes of the type (Me5C5)P=NR [R = C6H2tBu3 (5a), Si-i-Pr3 (5b), SiMe3 (5c)] are prepared via either thermolytic or base-promoted elimination reactions and characterized by analytical and spectroscopic methods. The x-ray crystal structures of 5a,b establish the presence of coordination isomerism of the cyclopentadienyl ring, which at the same time strongly alters the characteristics of the P-N multiple bond. For 5a, η1-attachment of the Me5C5 moiety to the phosphorus and a localized phosphorus-carbon σ-bond are found, and the P-N double bond compares to that of alkylated iminophosphanes (rPN = 155.1 (8) pm). 5b exhibits η2-coordination of the cyclopentadienyl ring leading to increased P-N triple-bond character, as evidenced by shortening of the P-N distance (153.3 (3) pm) and the remarkable opening of the nitrogen valence angle (153.3 (2)°). The structure is discussed as an intramolecular π-complex between a formal cyclopentadienyl anion and an iminophosphenium cation. The 1H and 13C NMR spectra show that rapid elementotropic rearrangements around the five-membered ring take place both in solution and in the solid state. The unique temperature dependence of δ31P in solution together with the considerable differences in δ 31P between the solution and solid states are interpreted in a model assuming a "haptotropic" mechanism for the fluxionality involving dynamic η1/η2-coordination isomerizations in solution. As expected, nucleophilic displacement of the Me5C5 moiety takes place in the reaction of 5b,c with LiC6H2tBu3, yielding the iminophosphanes tBu3H2C6P=NR (R = Si-i-Pr3 (8b), SiMe3 (c)) as products

Interface-engineered templates for molecular spin memory devices

The use of molecular spin state as a quantum of information for storage, sensing and computing has generated considerable interest in the context of next-generation data storage and communication devices(1, 2), opening avenues for developing multifunctional molecular spintronics(3). Such ideas have been researched extensively, using single-molecule magnets(4, 5) and molecules with a metal ion(6) or nitrogen vacancy(7) as localized spin-carrying centres for storage and for realizing logic operations(8). However, the electronic coupling between the spin centres of these molecules is rather weak, which makes construction of quantum memory registers a challenging task(9). In this regard, delocalized carbon-based radical species with unpaired spin, such as phenalenyl(10), have shown promise. These phenalenyl moieties, which can be regarded as graphene fragments, are formed by the fusion of three benzene rings and belong to the class of open-shell systems. The spin structure of these molecules responds to external stimuli(11, 12) (such as light, and electric and magnetic fields), which provides novel schemes for performing spin memory and logic operations. Here we construct a molecular device using such molecules as templates to engineer interfacial spin transfer resulting from hybridization and magnetic exchange interaction with the surface of a ferromagnet ; the device shows an unexpected interfacial magnetoresistance of more than 20 per cent near room temperature. Moreover, we successfully demonstrate the formation of a nanoscale magnetic molecule with a well-defined magnetic hysteresis on ferromagnetic surfaces. Owing to strong magnetic coupling with the ferromagnet, such independent switching of an adsorbed magnetic molecule has been unsuccessful with single-molecule magnets(13). Our findings suggest the use of chemically amenable phenalenyl-based molecules as a viable and scalable platform for building molecular-scale quantum spin memory and processors for technological development

Unusual formation of a N-heterocyclic germylene via homolytic cleavage of a C-C bond

Deutsche Forschungsgemeinschaft [RO 224/60-1]; Danish National Research Foundation [DNRF93]; Centre for Materials Crystallography; Norwegian Research Council through the CoE Centre for Theoretical and Computational Chemistry (CTCC) [179568/V30]; China Scholarship Council; Norwegian Supercomputing Program (NOTUR) [NN4654K]Reaction of the monoanionic radical salt IP center dot-K+ (IP = (Py)CH(=NR); Py = C5H4N, R = 2,6-iPr(2)C(6)H(3); alpha-iminopyridine) with GeCl2(dioxane) afforded compound (IPGeCl)(2) (1) which produced red blocks of IPGe: (2), when treated with KC8 in toluene. 1 is a digermylene formed via C-C coupling between two carbon-centered radicals. 2 can be considered as an analogue of a N-heterocyclic carbene, which exhibits a five-membered GeC2N2 ring with one CQC double bond. 2 is formed by two-electron reduction of 1 with cleavage of the two Ge-Cl bonds and the central C-C single bond

Synthesis and Crystal Structure of a Copper(II) Benzoate Complex Bearing a Bis-2,2′-Tetrahydrofuryl Peroxide Moiety

Complex [Cu2(ben)4·2THF−(η1–O2)]∞ (2) (ben=C6H5CO2− benzoate; THF=tetrahydrofuran) was isolated when a solution of Cu2(ben)4·2THF (1) in THF upon natural sunlight irradiation yields crystals suitable for single-crystal X-ray diffraction analysis. 2, crystallized in the C2/c monoclinic space group, Z=8, V=3394.2 (4) Å3, and the unit cell parameters a=9.7935(7) Å, b=19.0055 (13) Å, c=18.2997 (13) Å, α=90°, β=94.7996 (11)º and γ=90°. This is the first example of a polymeric copper(II) carboxylate compound stabilizing a peroxo group via its apical ligand (THF molecule). Additionally, 2 was also characterized by elemental analysis, Fourier-transformed infrared spectroscopy (FTIR) and Raman spectroscopyUniversidad de Costa Rica/[804-B7-279]/UCR/Costa RicaUniversidad de Costa Rica/[804-B0-650]/UCR/Costa RicaUCR::Vicerrectoría de Docencia::Ciencias Básicas::Facultad de Ciencias::Escuela de QuímicaUCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Básicas::Centro de Investigación en Electroquímica y Energía Química (CELEQ