Henrique C. S. Junior

Federal University of Rio Grande do Sul | UFRGS · Institute of Chemistry

Nonsymmetric 2-aryl (benz)imidazole derivatives were previously synthesized via C-H/N-H annulation of imidazole derivatives from lapachol moieties with internal alkynes as an efficient tool to increase the π-system of lapimidazole derivatives. To investigate their photophysical properties, time-resolved and steady-state fluorescence measurements we...

2,5-Di(hetero)arylthiophenes are key structural scaffolds for several emissive applications and offer tunable fluorescent features attributed to their π-conjugated structures and versatile substituents. In this context, we assessed the photoluminescence of 2,5-di(hetero)arylthiophene derivatives synthesized from 1,3-diynes through cyclization react...

1,3-Dithiole-2-thione-4,5-dithiolate (dmit) ligands are known for their conductive and optical properties. Dmit compounds have been assessed for use in sensor devices, information storage, spintronics, and optical material applications. Associations with various metallic centers endow dmit complexes with magnetic, optical, conductive, and antioxida...

In this study, we present a comprehensive photophysical investigation of ESIPT-reactive benzazole derivatives in both solution and the solid state. These derivatives incorporate different chalcogen atoms (O, S, and Se) into their structures, and we explore how these variations impact their electronic properties in both ground and excited states. Ch...

Lophine-benzothiazole dyads were synthesized via the amine-isocyanate reaction involving N-alkylamino lophine and 2-(5′-isothiocyanate-2-hydroxyphenyl)benzothiazole. The resultant coupling generated a thiourea linkage, connecting the two primary fluorophores with varying chain lengths (2 and 8 methylene groups). These newly formed dyads exhibit dis...

In this work, we present a series of chromophores based on dialkynyl‐N‐(het)arylpyrrole, featuring diverse combinations of donor‐acceptor moieties. The study explores the potential of fluorophores derived from (alkynyl)arylpyrroles, investigating the impact of the central core‘s nature with phenyl and pyridyl groups, along with various arylethynyl...

A series of mononuclear lanthanide-based coordination compounds was obtained under mild synthetic conditions and fully characterized. Single-crystal X-ray diffraction reveals six isomorphic compounds of type [Ln(NO3)(4picH)2(H2O)4](NO3)2 (Ln3+ = Sm (1), Eu (2), Gd (3), Tb (4), Dy (5), Er (6)), in which 4picH is the zwitterionic form of the 4-picoli...

Estimating the magnetic anisotropy for single-ion magnets is complex due to its multireference nature. This study demonstrates that deep neural networks (DNNs) can provide accurate axial magnetic anisotropy (D) values, closely matching the complete-active-space self-consistent-field (CASSCF) quality using density functional theory (DFT) data. We cu...

Context: Triazene compounds (-NNN(H)-) exhibit versatility in biological, physical, and chemical applications. In their anionic form (-NNN-)(-), they can act as coordinating sites for metals, forming metallic complexes. In this study, two new isomeric triazene compounds with meta- and para-substituents in their neutral and anionic forms were inves...

This study presents a comprehensive analysis of the synthesis and photophysical properties of thiazolidine-functionalized chiral ionic liquids (CILs) derived from L-cysteine. The synthesis involves a four-step route, encompassing N-protection, coupling reactions with bromoalco-hols, and ionic liquid formation. The optical properties of the compound...

In this study, we present the synthesis of benzimidazo[1,2-a] quinoline-based heterocycles bearing organosulfur and organoselenium moieties through transition-metal-free cascade reactions involving a sequential intermolecular aromatic nucleophilic substitution (SNAr). Both sulfur and selenium derivatives presented absorption maxima located around 3...

We report herein an efficient, fast, and sustainable method for the preparation of fluorescent indolizine derivatives under ultrasound (US) irradiation using a one-pot and multicomponent methodology. In solution, the indolizine derivatives present absorption in the UV region and fluorescence emission in the violet-to-blue region with a relatively l...

This study describes the synthesis of new pyromellitic diimide (PMDI) derivatives obtained in good yields from the reaction between pyromellitic dianhydride and aminobenzazoles reactive to proton-transfer in the excited state (ESIPT). In this investigation, a non-ESIPT PMDI was also prepared for comparison. These compounds presented absorption maxi...

Here we present simple fluorophores based on the pyridine core, obtained with straightforward synthetic methodologies. These compounds present in solution absorption maxima in the UV region and fluorescence emission of between 300 and 450 nm, depending on the solvent and chemical structure of the fluorophore. The nature of the solvent was shown to...

Heptamethine cyanine dyes were synthesized in good yields by the reaction between quaternary indoles and a pentamethinic salt, under mild reaction conditions minimizing photoox-idation. These compounds were used as precursors to prepare meso-substituted derivatives. The cyanine dye precursors presented UV-Vis absorption, related to fully allowed el...

Herein we report on the preparation, spectroscopic and thermal characterization, structural study, and magnetic investigation of a new heterobimetallic coordination polymer (CP) of formula {[Na(H 2 O) 2 ][Cu 2 (bpca) 2 (CO 3 )(HCO 3 )]} n (1) [Hbpca = bis(2-pyridylcarbonyl)amide], which...

Herein a 1D Co(II) coordination polymer of formula [Co(η1-L1)(η2-L1)(py)2(H2O)]n (CoCP) has been synthesised using the rigid H2L1 proligand, containing a long spacer bearing two triple bonds. Single-crystal X-ray diffraction showed that Co(II) adopts a distorted octahedral geometry. The state-averaged complete active self-consistent field (SA-CASSC...

Two binuclear complexes of molecular formula [CoIICl(H3L)(H2O)]2Cl2 (1) and [CuIICl2(H3L)]2 (2), where H3L stands for the chiral ligand (2-pyridin-2-yl-1,3-oxazolidine-4,4-diyl)dimethanol) were obtained. The complexes and H3L ligand were formed using an one-pot strategy and characterized by spectroscopy techniques (FT-IR and UV-Vis), X-ray diffract...

Benzothiazole derivatives were used as models to study the excited-state intramolecular proton transfer (ESIPT) in an experimental and theoretical point of view. The experimental electronic and vibrational results were compared with a comprehensive selection of state-of-the-art computational methods in a workflow approach. These latter were perform...

A Cu( ii ) heptanuclear complex, Cu7atac , synthesized from an amino acid ligand showed to be an antiferromagnetic spin-frustrated bis-triangular system. Cu7atac might be a promising qubit candidate for quantum information storage.

Metal-dmit complexes and related compounds have been studied extensively over the last few decades. Experimental reports of its UV-Vis spectra present the main spectroscopic features, although many details of the electronic structure still have to be investigated. This work presents a detailed analysis of the UV-vis spectra of the [NEt4]x[M(L)3] (L...

Two coordination polymers with molecular formula 1∞[M(L)2(4,4’-bipy)(H2O)2]n, where M stands for CoII (1) or CuII, (2), and L = 5-amino-1-phenyl-1H-pyrazole-4-carboxylate ligand were obtained by slow solvent diffusion and characterized by spectroscopic techniques, single crystal and powder X-ray diffraction, magnetic measurements, and DFT calculati...

A series of three pseudo-octahedral coordination compounds with general formula cis-[M(L)2(OH2)4], where M stands for FeII (1), CoII (2) or NiII (3), and HL is 5-amino-1-(benzo[d]thiazol-2-yl)-1H-pyrazole-4-carboxylic acid proligand was synthesized by slow diffusion methodology and thoroughly characterized by spectroscopic techniques, magnetic meas...

Estudo ab initio da anisotropia magnética em compostos mononucleares

Description of the workflow used when structures obtained by X-Ray diffraction are used as molecular descriptors form multirreferencial calculations.

Can a Fractional Orbital Density (FOD) analysis be used as a tool to select the best orbitals for a CASSCF calculation? Orbitals selected as Active for CASSCF by a FOD analysis showed excellent agreement with the experimental reference, proving that the methodology is reliable.

The synthesis, crystal structure, magnetic properties and DFT calculations of a new mononuclear copper(II) complex containing a pyrazole-based ligand are reported. In the crystal structure of the [CuCl2L2] complex (L = Ethyl 5-amino-1-(4-methoxyphenyl)-1H-pyrazole-4-carboxylate), a network of hydrogen bonds connects the molecular units in the cryst...

Molecular Magnetic Compounds: Calculating Magnetic Couplings Using the DFT Method

In this work we describe the synthesis, crystal structure and magnetic properties of a new hexanuclear copper(II) containing compound. The crystal structure of the complex consists of a three steps ladder framework in which three [Cu(OMe)(fta)]2 dinuclear units (fta = 2-furoyltrifluoroacetonate) are connected to each other by methoxide bridges in a...

Elucidação das propriedades magnéticas utilizando o método DFT em um novo composto de coordenação de CuII contendo ligantes pirazólicos substituídos

A short review (in Portuguese) about the use of metal complexes of Cu and Zn as antitumoral agents.

Using DFT methods, hexaaquairon(II) and (III) are compared and the spontaneous oxidation from Iron(II) to Iron(III) is investigated.

Uma avaliação sobre métodos de análise da água considerada potável e os efeitos que a falta da mesma pode ter na sociedade e no desenvolvimento humano.

Uma análise do funcionamento de trocadores de calor e sua aplicação em usinas de geração de eletricidade.