Vinicius Tadeu Santana

Central European Institute of Technology-Czech Republic | CEITEC · CEITEC BUT

We present a theoretical and experimental study of two tetracoordinate Co(II)-based complexes with semi-coordination interactions, i.e., non-covalent interactions involving the central atom. We argue that such interactions enhance the thermal and structural stability of the compounds, making them appropriate for deposition on substrates, as demonst...

The widely used coelenterazine-powered Renilla luciferase was discovered over 40 years ago, but the oxidative mechanism by which it generates blue photons remains unclear. Here we decipher Renilla-type catalysis through crystallographic, spectroscopic and computational experiments. Structures of ancestral and extant luciferases complexed with the s...

Fourier-transform infrared (FTIR) magneto-spectroscopy is a powerful spectroscopic technique used to investigate many important effects in materials, e.g., electron spin resonance, cyclotron resonance, and transitions between Landau levels. Despite their enormous potential in material science, infrared magneto-spectrometers are still relatively rar...

Two novel hexacoordinate Co(II)-based single-ion magnets were prepared and characterised. Both neutral complexes feature the metal centre coordinated with one terminal and one bidentate nitrate anions along with tridentate derivatives...

The widely used coelenterazine-powered Renilla luciferase was discovered over 40 years ago but the oxidative mechanism by which it generates blue photons remains unclear. Here we decipher Renilla-type bioluminescence through crystallographic, spectroscopic, and computational experiments. Structures of ancestral and extant luciferases complexed with...

Consumption of fruits, including seeds and peels, provides some natural products that can act as antioxidant molecules and assist in combating oxidative stress. In recent years, the coordination of natural products to different metal centers of both s-p and d-block metals has been applied as a strategy to optimize their antioxidant activity. In add...

Four pentacoordinate complexes 1-4 of the type [Co(L1)X2] and [Co(L2)X2] (where L1=2,6-bis(1-octyl-1H-benzimidazol-2-yl)pyridine for 1 and 2, L2=2,6-bis(1-dodecyl-1H-benzimidazol -2-yl)-pyridine for 3 and 4; X = Cl- for 1 and 3, X...

Electron spin resonance (ESR) is a powerful spectroscopic technique used to investigate samples with unpaired electrons in a broad range of scientific fields. High-frequency ESR (HF-ESR) spectrometers operating at sub-THz frequencies are mostly custom-made with non-standard solutions. This article presents a set of six different exchangeable sample...

This study reports the photochemical behavior of fac‐[Mn(phen)CO3(4MeImH)]+ in neutral aqueous solution. The complex presents two 4MeImH linkage isomers, adjacent (A) and remote (R), which coexist in solution although with marked stability differences. In water, the steric effect converts A into an aqua‐complex while R remains stable. Photolysis of...

In the “Comment on article by Gonzaga et al. J Am Ceram Soc. 2020;103:6280‐6288”, Paparazzo argues that the estimated value of Ce3+ amount in our CeO2 samples through X‐ray photoelectron spectroscopy (XPS) analysis is ~10% and there is no dependence on the annealing temperature or Pr‐doping. However, a comparison of our XPS Ce3d spectra with the re...

The manganese Schiff-base complexes were applied in the OMRP of vinyl acetate.

Starting from its discovery, electron paramagnetic resonance (EPR) is a constantly developing technique following technological advances in generation and detection of microwaves, creation of strong magnetic fields, and fast digitalization, among others. In this chapter, we discuss developments in the field of high-frequency EPR (HFEPR) with a spec...

Biodiesel is considered a renewable fuel that has been replacing diesel. However, its degradation, caused by a radical reaction, is one of the biggest concerns about this fuel. Spin trapping is a useful resource to evaluate the radical formation in a sample. In the present work, the biodiesel degradation from canola, corn and soybean oils, with syn...

The development of stable and reproducible inorganic pigments is noteworthy for industrial applications mainly considering more intense shades and low toxicity. Among the various candidates to substitute non‐hazardous red and yellow pigments, CeO2 and CeO2:Pr have been attracting attention because of their opacity and high‐temperature stability bes...

X-ray structure and EPR spectra of two dinuclear copper compounds allow us to study spin entanglement and quantum phase transitions. Their different 3D arrays and interdinuclear exchange paths produce important effects.

A structurally new heptadentate derivative of a 15-membered pyridine-based macrocycle containing two benzimidazol-2-yl-methyl N-pendant arms (L = 3,12-bis((1H-benzimidazol-2-yl)methyl)-6,9-dioxa-3,12,18-triazabicyclo[12.3.1]octadeca-1(18),14,16-triene) was synthesized and its complexes with the general formula [M(L)](ClO4)2·1.5CH3NO2 (M = MnII (1),...

The scalability and stability of molecular qubits deposited on surfaces is a crucial step for incorporating them into upcoming electronic devices. Herein, we report on the preparation and characterisation of a molecular quantum bit, copper(ii)dibenzoylmethane [Cu(dbm)2], deposited by a modified Langmuir-Schaefer (LS) technique onto a graphene-based...

This research evaluated the formation of free radicals in the oxidative degradation of biodiesel in contact with metallic copper and metal alloys via EPR using the spin trapping PBN, identifying and quantifying the formation of free radicals in commercial biodiesel samples. The biodiesel samples were analyzed in contact with carbon steel, silver st...

We report the preparation, X-ray structure, chemical properties, and electron paramagnetic resonance (EPR) studies at Q and X-bands and temperature (mainly) T = 293 K of powder and oriented single crystal samples of the new compound [Cu(N0,N0-dimethyl-N0-benzoylthiourea)(2,20-bipyridine)Cl], called CuBMB. The EPR spectra of single crystal samples a...

We report the preparation, X-ray structure, chemical properties, and electron paramagnetic resonance (EPR) studies at Q and X-band, and temperature (mainly) T = 293 K, of powder and oriented single crystal samples of the new compound [Cu(N',N'-dimethyl-N'-benzoylthiourea)(2,2'-bipyridine)Cl], called CuBMB. The EPR spectra of single crystal samples...

Biodiesel is an environmentally friendly alternative for petro-diesel. However, its degradation caused by radical oxidative reactions generates free radicals that damage the mechanics of vehicles. Spin trapping is a powerful resource for quantifying the short-lived and unstable free radicals liberated in these reactions. In this work, the formation...

The combination of visible-light and tris(trimethylsilyl)silane promoting intramolecular reductive cyclization protocol for the synthesis of functionalized indolines and 2,3-dihydrobenzofurans has been developed.

This study reports the extension and implications of medium on the aggregation process of the [Ru(phen)2(pPDIp)]2+ complex and its consequences on photochemical and photophysics properties. Photolysis leads, initially, to emission of both chromophores: 3*MLCT (Ru,dpi→phen,pi*) and 1*ILCT (pPDIp,pi→pi*); however, the medium induces increased pi‐pi i...

This study describes the synthesis and characterization of three α-diimine-cobalt complexes of the type [CoCl2(R-DAB)] (R-DAB = R–N[dbnd]CH–CH[dbnd]N–R; R = Mes, Dipp and Dipp∗) and their application as mediators for the cobalt-mediated radical polymerization (CMRP) of vinyl acetate (VAc) using 2,2′-Azobis(2-methylpropionitrile) (AIBN) as initiator...

We report a variation with temperature (T ) of the effective interdimeric interaction J′eff in the antiferromagnetic (AFM) copper dimeric organic compound Cu2[TzTs]4 [N-thiazol-2-yltoluenesulfonamidate CuII]. This T dependence was obtained from measurements of the effects in the electron paramagnetic resonance (EPR) spectra of the proposed quantum...

Numerous applications have been described for microperoxidases (MPs) such as in photoreceptors, sensing, drugs, and hydrogen evolution. The last application was obtained by replacing Fe(III), the native central metal, by cobalt ion and inspired part of the present study. Here, the Fe(III) of MP-11 was replaced by Cu(II) that is also a stable redox...

Abstract Multi-frequency electron spin resonance (ESR) measurements in polycrystalline samples of BiMn2O5 were employed to observe antiferromagnetic resonances (AFMR) in the range 0–14 T below the Néel temperature. The experimental data were analyzed using the phenomenological theory of Yosida and Nagamiya. Three resonance modes were identified in...

X-band electron spin resonance (ESR) measurements have been performed on a conducting free-standing film of polyaniline plasticized and protonated with di-n-dodecyl ester of sulfosuccinic acid (DDoESSA). The magnetic field was applied parallel and perpendicular to the plane of the film. At around 75 K a transition is observed from Pauli susceptibil...

This study investigated the microbial action in soil on poly(L-lactic acid) (PLLA) and polyvinyl chloride (PVC) films and a PLLA/PVC 7 : 3 blend, using Fourier transform infrared spectroscopy (FTIR), contact angle and scanning electron microscopy (SEM). The films (50 μm) were obtained from the evaporation of dichloromethane solutions and buried in...

Resumo Analyzing the EPR spectra of a selfstanding conducting polymer film we noticed the asymmetry of the first derivative of the EPR line, suggesting that we should use a Dysonian line. This Dysonian line can be represented by a combination of absorption and dispersion Lorentzian lines. However we noticed that adding a small Gaussian line would...