This work reports the study of the anion effect on the aggregation behavior of the long-chain spacers of dicationic imidazolium-based ionic liquids (ILs) in a 4.75 % (
v
/
v
) ethanol-water solution ...as well as in ethanol (95 %). The anions studied were Br
−
, NO
3
−
, BF
4
−
, SCN
−
and NTf
2
−
. Aggregation behavior was investigated by differential scanning calorimetry (DSC), conductivity, surface tension, and fluorescence. In the ethanol-water solution, the critical aggregation concentration (CAC), free energy aggregation (∆
G
°
a
), and the ionization degree (α) all significantly decreased with the increase in anion hydrophobicity. In ethanol, the CAC and ∆
G
°
a
values also decreased with the increase in anion size and hydrophobicity. The free energy adsorption (∆
G
°
ads
) data showed that the dicationic ILs have good surfactant activity, and this property improved with the decrease in the hydration radius of the anions. The anion volumes calculated also showed a good correlation with the CAC values for aggregation in ethanol-water solution and ethanol.
Graphical Abstract
Favored aggregation of imidazolium based dicationic ILs by the increase in the anion hydrophobicity
The synthesis and structural elucidation of a new series of six 6-amino-2-alkyl(aryl/heteroaryl)-4-(trifluoromethyl) quinolines are reported, yielding 22 to 87% isolated products. This was achieved ...through a regioselective intramolecular cyclization reaction of novel (
Z
)-4-((4-aminophenyl)amino)-1,1,1-trifluoro-but-3-en-2-ones in an acidic solvent-free medium, in which alkyl/aryl/heteroaryl = methyl, phenyl, 4-MeC
6
H
4
, 4-FC
6
H
4
, 4-NO
2
C
6
H
4
, and 2-furyl. The novel compounds were fully characterized by
1
H-,
13
C- and
19
F-NMR spectroscopy, GC-MS and single-crystal X-ray diffraction. In addition, the preliminary investigation of photophysical properties of the 6-aminoquinolines (UV-Vis, fluorescence, quantum yield calculations, Stokes shifts, and TD-DFT analysis) and inhibitory activity against
M. tuberculosis
H37Rv strain was also presented. Thermal analyses were carried out to assess their properties as new materials.
Novel 2-aryl(heteroaryl)-6-amino-4-(trifluoromethyl)quinoline scaffolds with promising photophysical, thermal and antimycobacterial properties are reported.
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 simple and regioselectively controlled method for the preparation of both 1,4- and 1,6-regioisomers of 1-substituted 4(6)-trifluoromethyl-pyrimidin-2(1H)-ones is described. Both regioisomers were ...synthesized from the cyclocondensation reaction of 4-substituted 1,1,1-trifluoro-4-methoxybut-3-en-2-ones: with nonsymmetric ureas for the 1-substituted 4-(trifluoromethyl)pyrimidin-2(1H)-ones (1,4-isomer) and with nonsymmetric 1-substituted 2-methylisothiourea sulfates for the synthesis of 1-substituted 6-(trifluoromethyl)pyrimidin-2(1H)-ones (1,6-isomer). Each method furnished only the respective isomer in very good yields. The structure of the products was assigned based on the 1H and 13C NMR as well as 2D HMBC spectral analysis.
Supramolecular gels present several applications in which the gelator properties are closely dependent on their structure and solvent. Despite this, there are few studies on the effect of the ...gelation ability of gelators with slight molecular changes. Therefore, N-arylestearamides (in which aryl = phenyl (1), 4-tolyl (2) and 4-acetylphenyl (3)) were evaluated in different solvents. The critical gelefication concentration (CGC) values indicated that the substituents can significantly affect the concentration at which the supramolecular gels are formed, mainly in non-aromatic solvents (e.g. cyclohexane, acetonitrile and DMSO). From UV-Vis and DSC data, we verified that the gel-sol and sol-gel transitions (Tgel-sol and Tsol-gel) increase in the order of 1 < 2 < 3. Organogel strength was evaluated for 1-3 as a function of concentration and solvent type using rheology data. Gel strength is concentration-dependent and a strength order was found in acetonitrile, cyclohexane and DMSO, in which: 1 ∼ 2 > 3. Dynamic viscoelastic measurements as a function of temperature sweeps indicate a predominantly enthalpic contribution to the elasticity of the organogels formed from 1-3. Temperature-dependent 1H NMR indicates that NHO interactions may be responsible for the molecular association of molecules into 1D fibers, while 3D fibers were formed from van der Waals interactions.
A concise method to synthesize 1-substituted 4-amino-2-(trifluoromethyl)-1H-pyrroles from the heterocyclization reaction of 5-bromo-4-methoxy-1,1,1-trifluoropent-3-en-2-ones with amines is described. ...This method has the following advantages: it uses a wide range of primary amines, starting materials are easily available, it is simple to perform, the reaction conditions are mild, it is environmentally friendly, and it furnishes yields of up to 98%.
Extensive investigation of interactions and aggregation properties of IL + API systems is necessary to apply ionic liquids (ILs) with different hydrophobic characteristics to drug delivery or in ...active pharmaceutical ingredient (API) formulations. Therefore, this study aims to investigate the heteroassembly between dicationic ILs (BisOct(MIM)22X, in which X is Br or BF4, and BisOct(BnIM)22Br), both in the absence and the presence of neutral APIs (salicylic acid, ibuprofen, and paracetamol) with different functional groups. Isothermal titration calorimetry results demonstrate that IL–API associations occur at very low concentrations of IL. These results were reinforced by electrospray ionization mass spectrometry with variable collision-induced dissociation, in which the IL dication interactions with APIs were detected. The strength of the dication–API interaction was determined from E cm,1/2 data. The aggregation parameters (cac, ΔG agg °, and K) between ILs and APIs were evaluated by conductivity. The 1H NMR data showed that differences in chemical shifts provided relevant insights about interaction sites in both components.
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.
An efficient synthesis methodology for a series of tetrazolo1,5-
pyrimidines substituted at the 5- and 7-positions from the cyclocondensation reaction CCC + NCN was developed. The NCN corresponds to ...5-aminotetrazole and CCC to β-enaminone. Two distinct products were observed in accordance with the β-enaminone substituent. When observed in solution, the compounds can be divided into two groups: (a) precursor compounds with R = CF
or CCl
, which leads to tetrazolo1,5-
pyrimidines in high regioselectivity with R at the 7-position of the heterocyclic ring; and (b) precursor compounds with R = aryl or methyl, which leads to a mixture of compounds, tetrazolo1,5-
pyrimidines (R in the 5-position of the ring) and 2-azidopyrimidines (R in the 4-position of the ring), which was attributed to an equilibrium of azide-tetrazole. In the solid state, all compounds were found as 2-azidopyrimidines. The regiochemistry of the reaction and the stability of the products are discussed on the basis of the data obtained by density functional theory (DFT) for energetic and molecular orbital (MO) calculations.
A systematic investigation to assess the degree of similarity between polymorphs was carried out. A similarity indices (IX) approach was applied in ten series of polymorphs with different ...characteristics and number of molecules in the asymmetric unit. Geometric (ID), contact area (IC), and stabilization energy (IG) parameters were used. It was possible to situate each comparison in different regions of similarity within the polymorphism phenomenon and determine the boundaries between quasi-isostructural polymorphs and polymorphs of low similarity. The multiparameter IDCG index was used as a robust tool to determine the total similarity within the polymorphism phenomenon. The highest contribution of the stabilization energy parameter (45%) toward the final value of similarity (IDCG) was observed, followed by the contact area index (32%). The geometric index contributed approximately 23% to the final value of IDCG. This information reinforces the importance of the contact area and stabilization energy in assessing the degree of similarity between crystalline structures. A new descriptor (IQ) based on the comparison of the energetic contribution of intermolecular interaction types present in each crystal structure is presented. IQ can be a versatile tool and applicable even for systems that do not share any similarity.
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