RESUMO
Supramolecular aggregates formed through the association of an amphiphilic tetra-O-butylsulfonate calix[4]arene 1 were investigated in aqueous solution by a combination of different techniques (NMR, DLS and AFM). The ability of the micellar aggregates of calixarene 1 to increase the solubility of poorly water-soluble drugs was studied.
Assuntos
Calixarenos/química , Flurbiprofeno/química , Naproxeno/química , Ânions/química , Difusão Dinâmica da Luz , Espectroscopia de Ressonância Magnética , Micelas , Microscopia de Força Atômica , Estrutura Molecular , Solubilidade , Tensoativos/químicaRESUMO
The azobenzene unit used as a photochemically and thermally switchable linker in the assembly of a bis-calix[4]pyrrole receptor provides a means to modulate the binding of bis-carboxylates of significant biological importance in cancer research. Conversely, the complexation of different bis-anionic guests has significant kinetic effects on both the photochemical and thermal trans/cis isomerization of the azobenzene unit.
RESUMO
A small library of polytopic receptors has been synthesized from meso-p- and meso-m-aminophenylcalix[4]pyrroles and p- or m-phthaloyl or trimesic chloride. Selected bis-carboxylates and the citrate anion, which either exhibit altered distribution profiles in cancerous tissues in comparison with healthy tissues or are metabolites of carcinogenic substances (for example, trans,trans-muconic acid from benzene exposure in humans) were tested as ligands. Varied affinities and binding modes were observed as a function of the number of calix[4]pyrroles and the topology of amide units present in each of the polytopic receptors. The structures of the 1:1 complexes derived by molecular modeling are in excellent agreement with the results of (1)Hâ NMR complexation studies.
Assuntos
Amidas/química , Calixarenos/química , Ácidos Carboxílicos/química , Ácido Cítrico/química , Porfirinas/química , Ligação de Hidrogênio , Modelos MolecularesRESUMO
A meso-p-nitroaniline-calix[4]pyrrole derivative trans-coordinated to a Pt(II) center was synthesized and its structure solved by X-ray analysis. Adenosine monophosphate (AMP) was used as a model compound to evaluate the potential for the assisted delivery of the metal to the DNA nucleobases via the phosphate anion-binding properties of the calix[4]pyrrole unit. An NMR investigation of the kinetics of AMP complexation in the absence of an H-bonding competing solvent (dry CD(3)CN) was consistent with this hypothesis, but we could not detect the interaction of the calix[4]pyrrole with phosphate in the presence of water. However, in vitro tests of the new trans-calixpyrrole-Pt(II) complex on different cancer cell lines indicate a cytotoxic activity that is unquestionably derived from the coexistence of both the trans-Pt(II) fragment and the calix[4]pyrrole unit.
Assuntos
Antineoplásicos/síntese química , Calixarenos/química , Complexos de Coordenação/síntese química , Platina/química , Pirróis/química , Antineoplásicos/química , Antineoplásicos/farmacologia , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Complexos de Coordenação/química , Cristalografia por Raios X , Sistemas de Liberação de Medicamentos , Citometria de Fluxo , Humanos , Concentração Inibidora 50 , Espectroscopia de Ressonância Magnética , Modelos Moleculares , Estrutura MolecularRESUMO
The novel cryptand in/out-3, containing two tripyrrolemethane units bridged by three 1,3- diisopropylidenbenzene arms, was readily synthesized by a convergent three-step synthesis. It binds fluoride by inclusion with excellent selectivity with respect to a number of other tested anions. The structure of the free receptor and that of its fluoride complex were investigated in solution by NMR spectroscopy. The solid-state X-ray structure of the free cryptand 3 was also determined.
Assuntos
Calixarenos/síntese química , Pirróis/síntese química , Ânions/química , Sítios de Ligação , Calixarenos/química , Cristalografia por Raios X , Modelos Moleculares , Estrutura Molecular , Pirróis/química , EstereoisomerismoRESUMO
Calix[4]pyrrole (1), calix[2]m-benzo[4]pyrrole (2), 10alpha,20beta- and 10alpha,20alpha- bis(4-nitrophenyl)-calix[4]pyrroles 3 and 4, respectively, were found to exhibit various organocatalytic activities in the diastereoselective vinylogous addition reaction of 2-trimethylsilyloxyfuran (TMSOF, 7) to aldehydes. The gamma-hydroxybutenolide products are obtained in fairly good yields and with moderate diastereoselectivity. The structures of the catalysts, as well as the reaction conditions, strongly influence the efficiency of the reaction.
Assuntos
4-Butirolactona/análogos & derivados , Calixarenos/química , Porfirinas/química , 4-Butirolactona/síntese química , Aldeídos/química , Catálise , Furanos/química , Ligação de HidrogênioRESUMO
10alpha,20alpha-Bis(4-nitrophenyl)calix[4]pyrrole (1) forms 1:1 complexes with anions of selected aromatic hydroxy acids in which the host orientation within the guest is controlled by a change in the pH value. Some bis-anionic guests, including those obtained from 4-hydroxybenzoic acid, 1,4- and 1,3-benzenedicarboxylic acids, induce the self-assembly of molecular capsules involving two molecules of the receptor. (1)H NMR data and solid-state structures of the 1:1 complex of 1 with p-C(6)H(4)(COOH)(COO(-))(+)NMe(4) and the 2:1 capsule [(1)(2)m-C(6)H(4)(COO(-))(2)((+)NMe(4))(2)] provide structural details in solution and in the solid state.
RESUMO
Calix[2]benzo[4]pyrrole m-6 and p-6, each containing two dipyrromethane moieties and two m-phenylene or p-phenylene units, respectively, were readily synthesised from pyrrole, 1,3- and 1,4-bis(1,1'-dimethylhydroxymethyl)benzene, (m-4 and p-4, respectively) and acetone. Macrocycles m-6 and p-6 were tested as receptors for a selection of anions, such as acetate, dihydrogenphosphate and fluoride. The X-ray structures of m-6 and p-6 and those of the complexes m-6F(-), m-6Cl(-) and m-6CH(3)COO(-) (with an nBu(4)N(+) counterion) were also determined.
RESUMO
[structure: see text]. Tail-to-tail connection of two cone calix[5]arene moieties by a rigid p-xylyl spacer affords the new exoditopic receptor 3 featuring two pi-rich cavities (assembling cores) in a centrosymmetric divergent arrangement, as established by a single-crystal X-ray analysis. 1H NMR complexation studies of 3 with alkyldiammonium ions support the formation of discrete bis-endo-cavity complexes and/or capsular assemblies along a polymer chain (polycaps), according to the length of the connector.
Assuntos
Alcanos/química , Diaminas/química , Compostos Policíclicos/química , Benzenossulfonatos/química , Calixarenos , Reagentes de Ligações Cruzadas/química , Espectroscopia de Ressonância Magnética , Conformação Molecular , Estrutura Molecular , Espectrometria de Massas por Ionização por ElectrosprayRESUMO
Calix[6]pyrrole 2 and the "hybrid systems" calix[3]furan[3]pyrrole 12, calix[2]furan[4]pyrrole 13, and calix[1]furan[5]pyrrole 14, have been synthesized by increasing conversion of the furan units present in the readily accessible calix[6]furan 3 to pyrroles. The host-guest chemistry of these novel macrocycles towards a number of anions, including halogen ions, dihydrogen phosphate, hydrogen sulfate, nitrate, and cyanide has been investigated in solution by (1)H NMR titration techniques and/or phase transfer experiments. The solid-state structures of the free receptors 2, 12, and 13, the 1:1 complexes of calix[6]pyrrole 2 with chloride and bromide, and the 1:1 complex of 14 with chloride are also reported.
Assuntos
Íons/química , Substâncias Macromoleculares , Sítios de Ligação , Calixarenos , Cianetos/química , Furanos/síntese química , Furanos/química , Halogênios/química , Ligação de Hidrogênio , Espectroscopia de Ressonância Magnética , Estrutura Molecular , Nitratos/química , Fosfatos/química , Porfirinas/síntese química , Porfirinas/química , Pirróis/síntese química , Pirróis/química , Sulfatos/química , TitulometriaRESUMO
[reaction: see text] The meso-decamethyl-calix[5]pyrrole 2b was synthesized from the furan-based analogue 1b via the homologation of the furan rings to pyrrole, and its solid-state structure was determined by X-ray crystallography: surprisingly, the binding constant of 2b toward chloride is found to be lower than that of the tetrameric analogue 2a.