Improving the electroluminescence of [Zn(salophen)(OH2)] in polyfluorene-based light-emitting diode: the role of energy transfer and charge recombination

Combining two or more different compounds with advantageous properties has been a useful and straightforward strategy in achieving a new class of materials with improved physical properties. This has been especially true for electronic polymers, whose optoelectronic properties can be completely tuned, and even improved, when mixed with other polymeric materials, dye molecules and guest coordination compounds. Here, a light-emitting diode prepared with the conjugated polymer poly[(9,9-dioctylfluorenyl-2,7-diyl)-alt-co-(9,9-di-{5'-pentanyl}-fluorenyl-2,7-diyl)] (PFOFPen) as the host material and aquo[N,N'-bis(salicylidene)-o-phenylenediamine]zinc(II) ([Zn(salophen)(OH2)]) as the guest molecule was studied in terms of its photo and electroluminescence properties. The role of the ZnII coordination compound as a guest in the electroluminescence is discussed as a strategy for the improvement of the electroluminescence performance of coordination compounds using conjugated polymers as matrices. An additional advantage of these composites is that they are solution processable, a low-cost and time efficient alternative to vacuum vapor deposition. Additionally, the photophysical processes involved in both electroluminescence and photoluminescence emissions are discussed because they are markedly different.Combining two or more different compounds with advantageous properties has been a useful and straightforward strategy in achieving a new class of materials with improved physical properties. This has been especially true for electronic polymers, whose opt272295302FAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO2013/16245-2470529/2012-1The authors acknowledge FAPESP (2013/16245-2), CNPq (470529/2012-1), National Institute of Organic Electronics (INEO) (MCT/CNPq/FAPESP) and UNICAMP/FAEPEX for financial support and fellowship

Layer-by-layer films containing SiO2 nanoparticles as field-effect pH sensors

Devices for pH monitoring based on separative structures and high input impedance readout circuit were fabricated using silicon dioxide nanoparticles (SiO2-Np). SiO2-Np were self-assembled onto gold substrates via layer-by-layer (LbL) technique using poly(allylamine) hydrochloride (PAH) as the counter-ion. The pH sensing properties of PAH/SiO2-Np LbL films were examined upon buffer solutions from pH 2 to 12, exhibiting pH sensitivity in agreement with other pH sensitivity membranes based on SiO2. The presence of nanoparticles improved the electrode contact area, ideal for enzyme immobilization, suggesting that PAH/SiO2-Np are suitable platforms to be applied in field-effect based biosensors

Electronic and magnetic properties of the [Ni(salophen)]: an experimental and DFT study

FAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOFAPEMAT - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE MATO GROSSOCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOCAPES - COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOALThe effect of the coordination of a Ni(II) ion on the electronic and magnetic properties of the ligand salophen were experimentally and theoretically evaluated. The complex [Ni(salophen)] was synthesized and characterized through FTIR and an elemental ana92733FAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOFAPEMAT - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE MATO GROSSOCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOCAPES - COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOALFAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOFAPEMAT - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE MATO GROSSOCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOCAPES - COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL2013/16245-2214599/2015sem informaçãosem informaçãoThis research was suported by the Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP-grant 2013/16245-2), Fundação de Amparo à Pesquisa do Estado de Mato Grosso (FAPEMAT-grant 214599/2015), Conselho Nacional de Desenvolvimento Científico e Tecn

Electronic and magnetic properties of the [Ni(salophen)]: An experimental and DFT study

The effect of the coordination of a Ni(II) ion on the electronic and magnetic properties of the ligand salophen were experimentally and theoretically evaluated. The complex [Ni(salophen)] was synthesized and characterized through FTIR and an elemental analysis. Spectral data obtained using DMSO as a solvent showed that the ligand absorption profile was significantly disturbed after the coordination of the metal atom. In addition to a redshift of the salophen ligand absorption bands, mainly composed by π → π∗electronic transitions, additional bands of around 470 nm were observed, resulting in a partial metal-to-ligand charge transfer. Furthermore, a significant increment of its band intensities was observed, favoring a more intense absorption in a broader range of the visible spectrum, which is a desired characteristic for applications in the field of organic electronics. This finding is related to an increment of the planarity and consequent electron delocalization of the macrocycle in the complex, which was estimated by the calculation of the current strengths at the PBE0/cc-pVTZ (Dyall.v3z for Ni(II)) level