The pyrolysis of waste tire has been proposed as an alternative route to its recycling producing residual oils that can be used as fuels. In this work, a physicochemical process to obtain carbon-based dots (CBD) from carbon black (CBL) derivatives of tires is described. For this, the CBL was treated with different acids to produce CBL1 and CBL2 particles suspension. The pH of the suspension was adjusted to 5.6 to precipitate remaining impurities. Afterwards, the supernatant was ultra-centrifuged and the yellow pale solid, the purified CBD obtained by roto evaporation, was characterized by ultraviolet-visible spectrophotometer (UV-Vis), photoluminescence (PL) at 320-380 nm, high-resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), energy-dispersive X-ray spectroscopy (EDX), Fourier transform infrared microscopy (mFTIR), and X-ray photoelectron spectroscopy (XPS). This material showed the typical excitation wavelength dependent emission and a PL quantum yield of 19.29% and was constituted by a well-defined spherical shaped and single sheets of “graphene quantum dots” with undefined shape, with potential applications in optoelectronic and fluorescence imaging devices.

Uma nova espécie cobre(II)-tetra(3,4-piridil) porfirazina tetrarrutenada, [CuTRPyPz]4+ foi sintetizada e sua caracterização conduzida por meio de métodos analíticos, espectroscópicos e eletroquímicos. Sua extensa conjugação-À a distingue dos derivados análogos da meso-tetrapiridilporfirina, levando à ocorrência de interações eletrônicas mais fortes entre os complexos periféricos e o anel porfirazínico central. Com base nas interações eletrostáticas e de empilhamento-À, foram realizadas montagens, camada-por-camada, de filmes funcionais, combinando-se a [CuTRPyPz]4+ com a ftalocianina de cobre(II) tetrassulfonada, [CuTSPc]4-. As propriedades condutoras e eletrocatalíticas desses filmes foram investigadas através de técnicas de impedância e de voltametria de disco rotatório, observando-se um comportamento metálico nas proximidades do potencial do par redox Ru(III)/(II), bem como uma pronunciada atividade catalítica na oxidação de íons nitrito e sulfito, em meio aquoso.

A new tetraruthenated copper(II)-tetra(3,4-pyridyl)porphyrazine species, [CuTRPyPz]4+, has been synthesized and fully characterized by means of analytical, spectroscopic and electrochemical techniques. This À-conjugated system contrasts with the related meso-tetrapyridylporphyrins by exhibiting strong electronic interaction between the coordinated peripheral complexes and the central ring. Based on favorable À-stacking and electrostatic interactions, layer-by-layer assembled films were successfully generated from the appropriate combination of [CuTRPyPz]4+ with copper(II)-tetrasulfonated phtalocyanine, [CuTSPc]4-. Their conducting and electrocatalytic properties were investigated by means of impedance spectroscopy and rotating disc voltammetry, exhibiting metallic behavior near the Ru(III/II) redox potential, as well as enhanced catalytic activity for the oxidation of nitrite and sulphite ions.