HOMO Stabilisation in π‐Extended Dibenzotetrathiafulvalene Derivatives for Their Application in Organic Field‐Effect Transistors

Three new organic semiconductors, in which either two methoxy units are directly linked to a dibenzotetrathiafulvalene (DB‐TTF) central core and a 2,1,3‐chalcogendiazole is fused on the one side, or four methoxy groups are linked to the DB‐TTF, have been synthesised as active materials for organic field‐effect transistors (OFETs). Their electrochemical behaviour, electronic absorption and fluorescence emission as well as photoinduced intramolecular charge transfer were studied. The electron‐withdrawing 2,1,3‐chalcogendiazole unit significantly affects the electronic properties of these semiconductors, lowering both the HOMO and LUMO energy levels and hence increasing the stability of the semiconducting material. The solution‐processed single‐crystal transistors exhibit high performance with a hole mobility up to 0.04 cm² V^?1 s^?1 as well as good ambient stability.     

Platinum(II)–Gadolinium(III) Complexes as Potential Single‐Molecular Theranostic Agents for Cancer Treatment

Theranostic agents are emerging multifunctional molecules capable of simultaneous therapy and diagnosis of diseases. We found that platinum(II)–gadolinium(III) complexes with the formula [{Pt(NH₃)₂Cl}₂GdL](NO₃)₂ possess such properties. The Gd center is stable in solution and the cytoplasm, whereas the Pt centers undergo ligand substitution in cancer cells. The Pt units interact with DNA and significantly promote the cellular uptake of Gd complexes. The cytotoxicity of the Pt–Gd complexes is comparable to that of cisplatin at high concentrations (≥0.1 mM ), and their proton relaxivity is higher than that of the commercial magnetic resonance imaging (MRI) contrast agent Gd–DTPA. T₁‐weighted MRI on B6 mice demonstrated that these complexes can reveal the accumulation of platinum drugs in vivo. Their cytotoxicity and imaging capabilities make the Pt–Gd complexes promising theranostic agents for cancer treatment.     

On‐Surface Synthesis and Characterization of Triply Fused Porphyrin–Graphene Nanoribbon Hybrids

On‐surface synthesis offers a versatile approach to prepare novel carbon‐based nanostructures that cannot be obtained by conventional solution chemistry. Graphene nanoribbons (GNRs) have potential for a variety of applications. A key issue for their application in molecular electronics is in the fine‐tuning of their electronic properties through structural modifications, such as heteroatom doping or the incorporation of non‐benzenoid rings. In this context, the covalent fusion of GNRs and porphyrins (Pors) is a highly appealing strategy. Herein we present the selective on‐surface synthesis of a Por–GNR hybrid, which consists of two Pors connected by a short GNR segment. The atomically precise structure of the Por–GNR hybrid has been characterized by bond‐resolved scanning tunneling microscopy (STM) and noncontact atomic force microscopy (nc‐AFM). The electronic properties have been investigated by scanning tunneling spectroscopy (STS), in combination with DFT calculations, which reveals a low electronic gap of 0.4 eV.     

Interaction of alkyltin(IV) compounds with ligands of interest in the speciation of natural fluids: carboxylate and hydroxycarboxylate complexes of monomethyltin(IV) trichloride

The formation and stability of some carboxylate and hydroxycarboxylate (acetate, 1,2,3-propanetricarboxylate, 1,2,3,4-butanetetracarboxylate, malate and citrate) complexes of monomethyltin trichloride was studied potentiometrically at 25 degrees C and at different ionic strengths in NaNO3 aqueous solution. The following quite stable species are formed in the different systems (M = CH3Sn3+): ML(OH)+, ML2(OH)0, ML(OH)2(0) and M2L(OH)5(0) for acetate; MLH+, ML0, ML(OH)- and ML(OH)2(2-) for propanetricarboxylate; MLH2+, MLH0, ML-, ML(OH)2- and ML(OH)2(3-) for butanetetracarboxylate; ML(OH)0, ML(OH)2- and ML(OH)3(2-) for malate; ML0, ML(OH)-, ML(OH)2(2-) and ML(OH)3(3-) for citrate. Hydroxycarboxylate complexes are significantly stronger than simple carboxylate ones and this is likely to be due to the interaction of the -OH group in citrate and malate with monomethyltin(IV), whose strength was also quantified. It was found that the stability of these complexes can be roughly expressed by the simple relationship log K = a zeta, where zeta is the product of the charges of reactants and log K is the equilibrium constant. For simple carboxylic ligands we have a = 1.8 +/- 0.4 and, for hydroxycarboxylic ligands, a = 3.7 +/- 0.9. Other useful empirical relationships are reported. Moreover, hydroxycarboxylic complexes also play a prominent role in the speciation of monomethyltin(IV) under the pH conditions of interest for natural fluids.     

A proof of the normal form theorem for the closed terms of Girard's system F by means of computability

In this paper a proof of the normal form theorem for the closed terms of Girard's system F is given by using a computability method à la Tait. It is worth noting that most of the standard consequences of the normal form theorem can be obtained using this version of the theorem as well. From the proof-theoretical point of view the interest of the proof is that the definition of computable derivation here used does not seem to be well founded. MSC: 03F05, 03B15.     

The formation of proton and alkali metal complexes with ligands of biological interest in aqueous solution. Thermodynamics of Li+, Na+ and K+-dicarboxylate complex formation

The formation and stability of Li⁺, Na⁺ and K⁺ complexes with oxalate, malonate, succinate, maleate, DL-malate and phthalate were studied potentiometrically at various ionic strengths. From the data thus obtained, as well as from several literature data on the protonation of the above-mentioned ligands in various ionic media and at various temperatures, the dependence of Na⁺ and K⁺ complex formation on temperature was determined. The dependence on ionic strength, both for the protonation and the complex formation, is also discussed.     

Sopra l'esistenza dell'estremo per una classe di integrali curvilinei in forma parametrica

Sunto Mediante la semicontinuità l'A. perviene a teoremi di esistenza dell'estremo assoluto per problemi variazionali relativi a integrali curvilinei dello spazio in forma parametrica dipendenti dalle derivate di ordine non superiore al terzo. I risultati raggiunti provano l'efficacia dell'impostazione che l'A. ha dato a tali problemi in una Memoria recentemente pubblicata nei Rend. del Circolo Matematico di Palermo, e al tempo stesso pongono in luce sia differenze tra il problema del terzo ordine e quello del secondo ordine, sia, per questo ultimo problema, diversità tra gli integrali curvilinei dello spazio e quelli del piano, di cui l'A. si era occupato alcuni anni fa. A Giovanni Sansone nel suo 70^mo compleanno.     

Thomson scattering induced by gravitational waves

We investigate the effects of a weak gravitational wave, modelled as a gaussian wavepacket, on the polarization state of an electromagnetic field enclosed in a cavity. Our approach is semiclassical, in that the electromagnetic field is described as a quantum field, while the gravitational perturbation is treated classically, as a slightly curved background spacetime. Assuming that before the interaction the electromagnetic field has been prepared in a given polarization state, we show that – due to the gravitational scattering with the wave – some photons having different polarization states are found in the cavity at late times. Such polarization scattering has some resemblance with Thomson scattering, well-known in Quantum Electrodynamics: hence the motivation for the title. We give a numerical estimate of the resulting photon polarization spreading in the case of a typical gravitational burst from a final supernova rebound. We also briefly comment about the possible influence of such gravitational scattering on the Cosmic Microwave Background (CMB) polarization.