The supramolecular organization of organic salts has been widely researched, revealing recurring patterns in crystalline lattices that describe their supramolecular properties. In recent years, our ...research group has underscored the importance of considering the crystalline structures as a whole, incorporating all the necessary energetic and topological information for a comprehensive understanding of the crystalline system. Given this context, we investigated a series of ammonium mono- and dicarboxylate salts (
1-12
) to determine whether subtle structural modifications in the anionic organic component lead to relevant energy and topology changes in the crystalline lattice. To achieve this, we selected structures whose carboxylate anion only possesses an alkyl chain and is devoid of other functional groups. The ammonium cation (NH
4
+
) was fixed to determine the effect of variations in the alkyl chains of the selected mono- and dicarboxylates, such as length and degree of unsaturation. Additionally, probable crystallization mechanisms were proposed to elucidate some of the topological and energetic aspects involved in the crystallization of these compounds. Destabilizing interactions were observed in 10 crystalline structures, and the MEP data showed that the most destabilizing interactions occur by the proximity of portions with the same type of charge. Some dimers have unexpectedly low intermolecular interaction energies despite having large contact areas. Based on these data we demonstrate the additivity of intermolecular interactions, that is, the low intermolecular interaction energy in these dimers is the result of the sum of destabilizing energies and stabilizing energies. The cluster energy efficiency data revealed that most crystal lattices display typical characteristics of uncharged organic compounds. The proposed crystallization mechanisms showed a gradual increase in nucleus complexity in the initial stages and the total number of nucleation stages, resulting in five main patterns: monomer → 1D → 3D (
1-2
), monomer → dimer → 2D → 3D (
3
), monomer → 1D → 2D → 3D (
4-5
), monomer → dimer → 3D (
6
), and monomer → 2D → 3D (
7-12
).
The supramolecular organization of organic salts has been widely researched, revealing recurring patterns in crystalline lattices that describe their supramolecular properties.
The synthesis, structural analysis, and evaluation of the photophysical properties of twelve novel 2‐aryl(heteroaryl)‐6‐(4‐alkyl(aryl)‐1H‐1,2,3‐triazol‐1‐yl)‐4‐(trifluoromethyl)quinolines (6‐8), ...where aryl(heteroaryl)=Ph, 4‐Me‐C6H4, 4‐F‐C6H4 and 2‐ furyl; 4‐alkyl(aryl)=−CH2OH, −(CH2)5CH3 and Ph, are reported. Hybrid scaffolds 6–8 were synthesized at 77–95 % yields by regioselective copper‐catalysed azide‐alkyne cycloaddition (CuAAC) reaction of unpublished 6‐azido‐4‐(trifluoromethyl)quinolines (2) with selected terminal alkynes (3–5). Azido intermediates 2 were obtained from the reaction of 6‐amino‐4‐(trifluoromethyl)quinolines (1) and sodium azide at good yields (78–87 %). Compounds 6–8 were structurally fully characterized by 1H−, 13C− and 19F− and 1H−13C 2D‐NMR (HSQC, HMBC) spectroscopy, X‐ray diffraction (SC‐XRD) and HRMS analysis. Moreover, the photophysical properties, DNA‐ and HSA‐binding experiments (bio‐interactions), and molecular docking studies for compounds 6–8 were performed. These are discussed and compared with similar compounds from recent research.
Twelve novel hybridized 4‐trifluoromethyl‐(1,2,3‐triazol‐1‐yl)quinolines (6–8), were synthesized at 77–95 % yields by a regioselective copper‐catalysed azide‐alkyne cycloaddition (CuAAC), and characterized by NMR spectroscopy, and single‐crystal X‐ray diffraction (SC‐XRD) analysis. Subsequently, photophysical properties, BSA‐ and HSA‐binding experiments, and molecular docking studies for the new series 6–8 were performed. These are discussed, and compared with similar compounds from recent research.
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•Seven examples of 2-(1,5-diaryl-4,5-dihydro-1H-pyrazol-3-yl)phenols are synthesized.•Photophysical/Electrochemical properties of fluorescent 2-pyrazolines are studied.•The UV–Vis ...absorption/emission properties are performed in five solvents.•ESIPT effect and donor-acceptor substituent influence are investigated in detail.•The fluorescence lifetimes (TCSPC) increase according to the solvent polarity.
This paper describes the synthesis, structural study, and evaluation of electrochemical and photophysical properties by UV–Vis absorption and fluorescence emission analysis (solution and solid-state) of a series of eight 3,5-aryl-substituted 1-phenyl-2-pyrazolines (5), where 3-aryl = 2-OH-C6H4 (5a-g) or Ph (5h), and 5-aryl = Ph (a, h), 1-naphthyl (b), 4-Br-C6H4 (c), 4-F-C6H4 (d), 4-OCH3-C6H4(e), 4-NO2-C6H4 (f), 4-(N(CH3)2)-C6H4(g). The UV–Vis absorption properties of 2-pyrazolines were evaluated in DCM, MeCN, AcOEt, EtOH, and DMSO as the solvent and showed a fluorescence shift for the polar aprotic solvents. The steady-state fluorescence emission exhibited a band in the blue region when excited at the least energetic transition of each compound, although the excited-state intramolecular proton (ESIPT) effect was not detected. In the solid state, compounds presented similar behavior regarding absorption and emission properties compared to the solution assays. With the electrochemical analyses performed for the synthesized 2-pyrazolines, it was possible to conclude that the redox potentials were influenced by the electronic and steric effects of the substituents on the aryl rings and, according to the electronic nature of the substituents, which electron-donating groups were favored. Finally, the TD-DFT analyses revealed that all compounds had delocalized electron density throughout the 2-pyrazolines unit and were not influenced by the substituent bonded at C-5. Nonetheless, LUMO orbital analysis showed that only derivatives 5b and 5f have this localized density over the substituents.
An efficient one-pot transition metal-free procedure for the synthesis of new pyrazolo1,5-aquinoxalin-4(5H)-ones from easily prepared 1-(2-chlorophenyl-5-ethylcarboxylate)pyrazoles and various ...primary alkylamines is described. The key steps involved in the synthesis of the new 5,6-fused ring system are the formation of an amide intermediate followed by an intramolecular N-arylation reaction via nucleophilic aromatic substitution.
A new series of ten examples of Schiff bases, namely (
)-2-(((2-alkyl(aryl/heteroaryl)-4-(trifluoromethyl)quinolin-6-yl)imino)methyl)phenols
, was easily synthesized with yields of up to 91% from the ...reactions involving a series of 2-(R-substituted) 6-amino-4-(trifluoromethyl)quinolines
and 4(5)-R
-substituted salicylaldehydes
- in which alkyl/aryl/heteroaryl for 2-R-substituents are Me, Ph, 4-MeC
H
, 4-FC
H
, 4-NO
C
H
, and 2-furyl, and R
-substituents are 5-NEt
, 5-OCH
, 4-Br, and 4-NO
. Complementarily, the Schiff bases showed low to good quantum fluorescence yield values in CHCl
(Φ
= 0.12-0.80), DMSO (Φ
= 0.20-0.75) and MeOH (Φ
= 0.13-0.85). Higher values of Stokes shifts (SS) were observed in more polar solvents (DMSO; 65-150 nm and MeOH; 65-130 nm) than in CHCl
(59-85 nm). Compounds
presented good stability under white-LED irradiation conditions and moderate ROS generation properties were observed.
A regio‐ and chemoselective method for the preparation of 6‐trifluoromethyl‐5‐benzoyl‐2‐methylsulfanyl pyrimidines and their pyrimidin‐4(3H)‐one analogues, from the cyclocondensation reaction of ...trifluoromethyl β‐enamino diketones with non‐symmetric 2‐methylisothiourea sulfates is reported. These diketones functioned as dual substrates by providing both products with high regioselectivity (only N3‐substituted isomer was observed) and high chemoselectivity. A new feature provided by the starting material proposed herein is the possibility to either maintain or eliminate the trifluoromethyl group, by choosing the solvent.
A regio‐ and chemoselective method for the preparation of 6‐trifluoromethyl‐5‐benzoyl‐2‐methylsulfanyl pyrimidines and their pyrimidin‐4(3H)‐one analogues, from the cyclocondensation reaction of trifluoromethyl β‐enamino diketones with non‐symmetric 2‐methylisothiourea sulfates is reported.
A convenient synthesis of a broad series of thirteen examples of alkyne‐spacer derivatives 2 from the well‐known Sonogashira cross‐coupling reaction on diazenyl‐pyrazolo1,5‐apyrimidin‐2‐amine ...compounds 1 is reported. The reactivity of heterocycles 1 due the presence of selected electron‐donor (EDG) and electron‐withdrawing (EWG) groups attached to different alkynes was evaluated. Also, the reactional versatility due the position variation of the bromo atom at the scaffolds 1 was also investigated. In general, derivatives presented strong absorption bands at the 250–500 nm optical window and UV to cyan emission properties. Also, the redox analysis was recorded by electrochemical cyclic voltammetry technique. For HSA biomacromolecule assays, spectroscopic studies by UV‐Vis, steady‐state and time‐resolved emission fluorescence, and molecular docking calculations evidenced the ability of each compound to establish interactions with human serum albumin (HSA). Finally, the behavior presented for this new class of heterocycles makes them a promising tool as optical sensors for albumins.
The convenient synthesis of a broad series of versatile alkyne‐spacer derivatives from the well‐known Sonogashira cross‐coupling reaction on diazenyl‐pyrazolo1,5‐apyrimidin‐2‐amine compounds is reported. This new class of heterocycles makes a promising tool for optical sensors for albumins.
The synthetic potential of 5-bromo-1,1,1-trifluoro-4-methoxypent-3-en-2-one toward the catalyst-free synthesis of N-pyrrolyl(furanyl)-piperazines, 1,4-diazepanes, and 1,4-diazocanes through a ...telescoped protocol is reported. This three-component one-pot method provided 23 examples with high chemo- and regioselectivity at yields up to 96%.
The quest for understanding crystal structures using supramolecular cluster demarcation has been applied to various uncharged compounds, and, more recently, it has also been applied to charged ...compounds in ammonium salts. Given this context, this study sought to expand this approach for intermediate compounds, between compounds with and without localized charges. The selected structures were mesoionic compounds, which have delocalized charges. This study raises some questions: do mesoionic compounds have intermediate characteristics between salts and uncharged molecules? Or are they similar to one of these models? A molecular and supramolecular investigation of mesoionic models was carried out to answer these questions. The study was based on demarcating the supramolecular cluster, enabling us to propose the crystallization mechanisms of twenty-three mesoionic compounds, in which stabilizing and destabilizing energies were observed. In addition, the Cluster Energy Efficiency (CEE) parameter was applied, allowing us to quantitatively evaluate the similarity between compounds containing both stabilizing and destabilizing energies in the crystalline lattice. The CEE data revealed that most mesoionic compounds have CCE = 1000, a characteristic comportment of uncharged compounds. In addition, the compound 2,3-diphenyl-1,3,4-thiadiazolium-5-thiolate (
18
) was synthesized and characterized to better understand the molecular and supramolecular behavior. Concentration-dependent NMR and LC-MS/MS experiments reveal the first aggregates in solution in the crystallization process of compound
18
. The crystallization mechanisms evidenced six different crystallization patterns, and molecular electrostatic potential (MEP) allowed us to evaluate the different patterns of electrostatic potential dispersion of all compounds.
The quest for understanding crystal structures using supramolecular cluster demarcation has been applied to various uncharged compounds, and, more recently, to charged compounds. So, what would be the supramolecular behavior of mesoionic compounds?
Insights into the occurrence of packing and conformational polymorphs and anhydrous/hydrate forms of 1,2-bis(aminocarbonyl(1-tert-butyl-1H-pyrazol-35-yl))ethanes with the substituents R = Me (a), ...F-4-Ph (b), Cl-4-Ph (c), and Br-4-Ph (d) in positions 5 (1) and 3 (2) of the pyrazole rings are presented. In this series, two molecular forms were observed, linear and folded. Compound 1a revealed an illuminating and rare example of a highly flexible molecule with packing polymorphism. The molecular stacking and absence of NH···OC interactions promoted polymorph growth. Structure 2a showed chains driven by NH···OC bonds in the anhydrous form and closed dimers by water binding the molecules (NHamide···OHwt···COamide) in the hydrate form. Two different forms were observed for conformational polymorph 2d (linear and folded). The folded form was about −10 kcal mol–1 more stable than the linear form, showing significant crystalline packing differences. This occurrence is attributed to the rotation of the amide groups through the NH···OC bonds. The linear shape showed a higher stabilization energy for NH···OC bonds and a cluster −6 kcal mol–1 more stable than polymorph 2dI. Compounds 1b–d and 2b-c also had their crystal growth proposed and features highlighted.
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