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The photon upconversion based on sensitized triplet–triplet annihilation (sTTA-UC) is a spin-flip mechanism exploited to recover the energy stored on dark triplet states in conjugated systems. In this process, a high-energy fluorescent singlet is created through the collision and fusion of two low-energy triplets belonging to different diffusing molecules. Its high yield in solution under low excitation intensity and noncoherent light highlighted the huge potential of sTTA-UC to provide a breakthrough in solar technologies. However, its diffusion-limited nature restrains its efficiency in the solid state. To overcome this issue, we propose a single-molecule system that is able to host simultaneously more than one triplet, thus enabling a diffusion-free intramolecular TTA. We obtain the first direct demonstration of intramolecular triplet fusion by tailored photoluminescence spectroscopy experiments, thus opening the way to realize a new family of single-molecule upconverters with huge potential in solar and lighting technologies by accessing the natural triplets’ energy reservoir.

The photon upconversion based on sensitized triplet-triplet annihilation (sTTA-UC) is a spin-flip mechanism exploited to recover the energy stored on dark triplet states in conjugated systems. In this process, a high-energy fluorescent singlet is created through the collision and fusion of two low-energy triplets belonging to different diffusing molecules. Its high yield in solution under low excitation intensity and noncoherent light highlighted the huge potential of sTTA-UC to provide a breakthrough in solar technologies. However, its diffusion-limited nature restrains its efficiency in the solid state. To overcome this issue, we propose a single-molecule system that is able to host simultaneously more than one triplet, thus enabling a diffusion-free intramolecular TTA. We obtain the first direct demonstration of intramolecular triplet fusion by tailored photoluminescence spectroscopy experiments, thus opening the way to realize a new family of single-molecule upconverters with huge potential in solar and lighting technologies by accessing the natural triplets' energy reservoir.

The C, N and O 1s XPS spectra of uracil clusters in the gas phase have been measured. A new bottom-up approach, which relies on computational simulations starting from the crystallographic structure of uracil, has been adopted to interpret the measured spectra. This approach sheds light on the different molecular interactions (H-bond, pi -stacking, dispersion interactions) at work in the cluster and provides a good understanding of the observed XPS chemical shifts with respect to the isolated molecule in terms of intramolecular and intermolecular screening occurring after the core-hole ionization. The proposed bottom-up approach, reasonably expensive in terms of computational resources, has been validated by finite-temperature molecular dynamics simulations of clusters composed of up to fifty molecules., QC 20201118

We have investigated the atomistic structure and the electronic properties of selected metal-organic interfaces, commonly found in organic electronic devices, using ab initio simulations based on density functional theory. Our study focuses, in particular, on the interaction of a widely used p-type organic semiconductor (OS) like the [1]benzothieno[3,2-b][1]-benzothiophene (BTBT) polycyclic molecule with a gold electrode, bare or functionalized with a self-assembled monolayer (SAM) of aromatic thiol used as a surface modifier. A similar investigation involved an S,S'-tetraoxide derivative of BTBT indicated as BTBTOx2, showing promising characteristics as an n-type semiconductor, whose original synthetic protocol is also discussed. First, our simulations, including the ab initio calculation of dispersion forces that permits an accurate description of noncovalent interactions, show that minimal changes in local interactions can induce a different arrangement of the same molecules in contact with metal electrodes. In particular, we report a stronger adhesion of BTBT and BTBTOx2 on bare gold, with the molecules lying flat on the surface, and a stronger cohesion of the same organic adlayers on gold surfaces functionalized with an SAM, with the molecules that prefer to form stacks parallel to the surface, more similar to those observed in the corresponding molecular crystals. Moreover, the functionalization of the same gold surface with self-assembled molecular modifiers having different polarities induces changes in the electronic properties of the Au/BTBT and Au/BTBTOx2 interfaces, transforming the Schottky junctions formed when the molecules are in direct contact with the bare gold surface in more favorable Au/SAM/OS junctions characterized by a significant reduction of the injection barrier or even a nearly Ohmic contact when the SAM is applied, in both the p-type and n-type investigated cases.

The Suzuki-Miyaura cross-coupling reaction of 4,7-dibromo-5,6-difluoro-2,1,3-benzothiadiazole with different arylboronic acids can be efficiently carried out in water and under air by means of micellar coupling. The careful tuning of reaction conditions enables preparation of symmetrically and unsymmetrically substituted derivatives. The moderate to good yields obtained, along with the wide variety of available substitution patterns, makes this sustainable methodology very useful for the preparation of building blocks for luminescent optoelectronic materials

The Suzuki-Miyaura cross-coupling reaction of 4,7-dibromo-5,6-difluoro-2,1,3-benzothiadiazole with different arylboronic acids can be efficiently carried out in water and under air by means of micellar coupling. The careful tuning of reaction conditions enables preparation of symmetrically and unsymmetrically substituted derivatives. The moderate to good yields obtained, along with the wide variety of available substitution patterns, makes this sustainable methodology very useful for the preparation of building blocks for luminescent optoelectronic materials

A number of studies have investigated the properties of monomeric and double-decker phthalocyanines (Pcs) adsorbed on metal surfaces, in view of applications in spintronics devices. In a combined experimental and theoretical study, we consider here a different member of the Pcs family, the (RuPc)(2) dimer, whose structure is characterized by two paired up magnetic centers embedded in a double-decker architecture. For (RuPc)(2) on Ag(111), we show that this architecture works as a preserving cage by shielding the Ru-Ru pair from a direct interaction with the surface atoms. In fact, while noticeable surface-to-molecule charge transfer occurs with the ensuing quenching of the molecular magnetic moment, such phenomena occur here in the absence of a direct Ru-Ag coupling or structural rearrangement, at variance with other Pcs and thanks to the above shielding effect. These unique properties of the (RuPc)(2) architecture are expected to permit an easy control of the surface-to-molecule charge-transfer process as well as of the molecular magnetic properties, thus making the (RuPc)(2) dimer a significant paradigm for innovative "cage" structures as well as a promising candidate for applications in spintronics nano or single-molecule devices.

Salto en la foliación antigua de la h. 17 a la h. 19

Salto en la foliación antigua de la h. 17 a la h. 19