Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 160
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Dalton Trans ; 2020 May 27.
Artigo em Inglês | MEDLINE | ID: mdl-32458927

RESUMO

A new flexible and divergent 1,2,3-triazol-4-yl-picolinamide (tzpa) ligand 2 and the half-equivalent model ligand 1, both functionalised with pendant 3-pyridyl groups, are reported and their coordination behaviour with silver(i) ions is explored, both in the crystalline phase and through the formation of a supramolecular metallogel. The self-assembly of tzpa ligand 1 with AgCF3SO3 resulted in the formation of a 1D coordination polymer, binding in a bidentate fashion through the pyridyl and triazole nitrogen atoms of the tzpa binding site and a pendant pyridyl nitrogen atom of an adjacent ligand. Doubling the number of metal binding sites in ligand 2, while retaining the same metal binding domain, gives rise to the formation of a supramolecular metallogel on reaction with AgBF4 at 5 wt% in MeCN, possessing self-healing properties.

2.
Org Biomol Chem ; 18(18): 3475-3480, 2020 May 13.
Artigo em Inglês | MEDLINE | ID: mdl-32329760

RESUMO

An investigation into the self-assembly of two 4-amino- and a 4-bromo-1,8-naphthalimide (Nap) based structures (1-3) possessing an appended glycan unit, from protic polar media, is presented. The results demonstrate the formation of complex hierarchical luminescent aggregates, wherein the morphologies, sizes and spherical structures were highly dependent on both the media and the Nap structure. Upon cleaving the native glycosidic bond, using an enzyme, the structure/morphology of the self-assembly of 3 in buffered solution was significantly transformed.

3.
Inorg Chem ; 59(5): 2646-2650, 2020 Mar 02.
Artigo em Inglês | MEDLINE | ID: mdl-32049514

RESUMO

Ditopic helicate ligands 1 and 2 were synthesized for the formation of dinuclear EuIII luminescent chiral helical assemblies (Eu2·L3) in competitive organic and protic solvent media. Spectroscopic analysis revealed formation of the 2:3 (Eu2·L3) and 2:2 (Eu2·L2) species in methanolic solutions. Circular dichroism and circularly polarized luminescence (CPL) spectroscopy confirmed the chiral purity of the helical systems, while scanning electron microscopy imaging demonstrated the formation of hierarchical self-assemblies with spherical morphologies.

4.
Chem Commun (Camb) ; 56(17): 2562-2565, 2020 Feb 28.
Artigo em Inglês | MEDLINE | ID: mdl-32011616

RESUMO

The 4-amino-1,8-naphthalimide-Tröger's base fluorophore, TBNap-TPy, adorned with phenyl-terpyridine moiety was synthesised and assessed for its aggregation-induced emission (AIE) behaviour. TBNap-TPy was further employed as a fluorescent sensor for the discriminative sensing of π-electron-deficient nitroaromatic; the TBNap-TPy displaying the largest fluorescence quenching with high selectivity for picric acid, a harmful environmental pollutant widely used in the dye industries.

5.
Chem Commun (Camb) ; 55(81): 12140-12143, 2019 Oct 08.
Artigo em Inglês | MEDLINE | ID: mdl-31531424

RESUMO

The 4-amino-1,8-naphthalimide Tröger's base functionalized triazine covalent organic polymer TB-TZ-COP was synthesised and employed as a "turn-on" fluorescent and a colorimetric sensor for the discriminative sensing of volatile organic compounds; the TB-TZ-COP displaying the largest fluorescent enhancement and high sensitivity for 1,4-dioxane, a harmful environmental pollutant classified as a Group 2B carcinogen.

6.
Chem Commun (Camb) ; 55(64): 9523-9526, 2019 Aug 07.
Artigo em Inglês | MEDLINE | ID: mdl-31332405

RESUMO

The synthesis of a chiral bis-tridentate (1,2,3-triazol-4-yl)-picolinamide (tzpa) ligand is described and its coordination chemistry with Cu(NO3)2 and [Cu(MeCN)4]PF6 is explored in the crystalline phase as well as in solution. Chiral [2 × 2] tetranuclear square grid complexes [Cu4(H21)4](NO3)8 and [Cu4(H1)4](PF6)4 were observed, and crystallographically analysed, these being linkage isomers with N4O2 and N5O coordination spheres, respectively. These come about by an unusual in situ amide deprotonation and coordination, which accompanies a CuI → CuII oxidation process.

7.
Dalton Trans ; 48(30): 11317-11325, 2019 Aug 14.
Artigo em Inglês | MEDLINE | ID: mdl-31271402

RESUMO

The lanthanide directed self-assembly of chiral amphiphilic 2,6-pyridinedicarboxylic acid based ligands 1 and 2 with various Ln(CF3SO3)3 (Ln = TbIII, SmIII, LuIII, DyIII) salts was studied in CH3CN and evaluated with the expected 1 : 3 and 1 : 1 Ln : Ligand species forming in solution. Ligand chirality was retained and transferred, as depicted by circular dichroism (CD) and circularly polarised luminescence (CPL) measurements (for TbIII and SmIII), to the lanthanide centre upon complexation with high dissymmetry factor values for the SmIII complexes obtained (glum = -0.44 and 0.29 and 0.45 and -0.23 for the 4G5/2→6H5/2 and the 4G5/2→6H7/2 transitions of Sm·13 and Sm·23, respectively). The ability of the complexes to form stable Langmuir monolayers at the air-water interface was also established while Langmuir-Blodgett films of Tb·L3 and Sm·L3 exhibited lanthanide luminescent emission.

8.
J Org Chem ; 84(7): 4221-4228, 2019 Apr 05.
Artigo em Inglês | MEDLINE | ID: mdl-30880393

RESUMO

Herein, we present an example of covalent cages, whose flexible framework undergoes extending-shrinking motion under halide control. In the absence of halide anions, the free cage assumes a flattened conformation: the cavity is compressed along the C3 axis passing through the tertiary amines, and the two tribenzylamine platforms are eclipsed. Halide encapsulation promotes a large conformational rearrangement of the cage, involving an extension of the cavity along the C3 axis and shrinkage along the equatorial plane. Interestingly, the rearrangement is accompanied by the pyramidal inversion of the tertiary amines and by the rotation of the tribenzylamine-based platforms, which become staggered. The imidazolium-containing arms wrap around the spherical anion, leading to a racemic mixture of the M and P helical complexes. As expected from the flexible structure of the cage, the switch between the two limit conformations can be repeated for several cycles under alternating chemical stimuli (AgNO3/TBACl). This result is consistent with the low activation barriers determined by computational investigations. These also allowed us to quantify the energy difference between the shrunk and expanded cage conformations and to hypothesize an energetic pathway along which the conformational rearrangement can occur.

9.
Org Biomol Chem ; 17(8): 2287, 2019 02 20.
Artigo em Inglês | MEDLINE | ID: mdl-30702731

RESUMO

Correction for 'Glycosylated naphthalimides and naphthalimide Tröger's bases as fluorescent aggregation probes for Con A' by Elena Calatrava-Pérez et al., Org. Biomol. Chem., 2019, DOI: 10.1039/c8ob02980f.

10.
Org Biomol Chem ; 17(8): 2116-2125, 2019 02 20.
Artigo em Inglês | MEDLINE | ID: mdl-30629076

RESUMO

Herein we report the synthesis of fluorescent, glycosylated 4-amino-1,8-naphthalimide (Nap) 1, and the related 1,8-naphthalimides Tröger's bases (TBNap) 2 and 3, from 1,8-naphthalic anhydride precursors, the α-mannosides being introduced through the use of CuAAC mediated 'click' chemistry. We investigate the photophysical properties of these probes in buffered solution and demonstrate their ability to function as fluorescent probes for Concanavalin A (Con A) lectin. We show that both the Nap and TBNap structures self-assemble in solution. The formation of the resulting supramolecular structures is driven by head-to-tail π-π stacking and extended hydrogen bonding interactions of the Nap and the triazole moieties. These interactions give rise to spherical nano-structures (ca. 260 nm and 100 nm, for 1 and 3, respectively), which interact with the Con-A protein, the interaction being probed by using both luminescent and Scanning Electron Microscopy imaging as well as dynamic light scattering measurements. Finally, we show that these supramolecular assembles can be used as luminescent imaging agents, through confocal fluorescence imaging of HeLa cells of the per-acetylated version 2.

11.
Chem Commun (Camb) ; 55(12): 1754-1757, 2019 Feb 05.
Artigo em Inglês | MEDLINE | ID: mdl-30664130

RESUMO

Two lanthanide luminescent naphthyl-dipicolinic amide (dpa) methacrylate monomers for the synthesis of grafted supramolecular co-polymer gels (hydrogels), and their use as additional crosslinks in robust covalently cross-linked HEMA hydrogels is presented; the results demonstrate the importance of the ligand symmetry for the Eu(iii) emission from the hydrogels.

12.
Dalton Trans ; 47(48): 17266-17275, 2018 Dec 11.
Artigo em Inglês | MEDLINE | ID: mdl-30488925

RESUMO

Here we report the synthesis of two new 2-(2'-pyrazinyl)pyridine ligands, and explore their coordination chemistry with Cu(ii) and Ag(i) ions, leading to the discovery of metallosupramolecular architectures of surprising complexity. Differing only in the substitution pattern of a nitrophenyl substituent attached to the 4-pyridyl position, ligands L1 and L2 both form sulfate-bridged dinuclear complexes on reaction with copper sulfate, without coordination of the nitrogen atom at the pyrazine 4-position. However, on reaction with Ag(i), both ligands adopt bridging coordination modes which lead to dramatically different outcomes. Ligand L2 reacts with AgCF3SO3 to give a densely packed coordination polymer 3 of unusually low symmetry (Z' = 7), while the structural isomer L1 instead gives an octanuclear macrocycle 4 in the crystalline state. Macrocycle 4, containing crystallographically-defined solvent molecules within its central cavity as well as in the interstitial spaces, readily undergoes solvent exchange in a single-crystal-to-single-crystal transformation. This allows a direct comparison of guest solvent affinity from single component and mixed-component exchange solutions using a combination of X-ray diffraction, NMR and TGA techniques, revealing the fully reversible uptake and exchange preferences of this material.

13.
Dalton Trans ; 47(46): 16377-16387, 2018 Nov 27.
Artigo em Inglês | MEDLINE | ID: mdl-30379167

RESUMO

Combination of different properties has always proven effective in the generation of hybrid materials with novel interesting properties. Ln(iii) containing materials possessing multiple properties are useful in a wide range of applications. In this article, key and recent examples of metallo-supramolecular polymers in the formation of gels, soft polymeric materials and films are discussed. There is a focus on the use of trivalent lanthanide, Ln(iii), ions to provide soft materials with advanced mechanical and luminescence properties for applications in developing electronic- and bio-technologies. This frontier article has been written with the intention of reaching a broad range of readers from various backgrounds such as chemistry, materials chemistry, spectroscopy and biochemistry. Additionally, we evaluate how the unique and versatile properties of such hybrid materials can be tuned and explored to enhance the efficiency, as well as research, for new ones. Finally, an assessment of the current state-of-the-art and our outlook for the future of this field is made.

14.
J Org Chem ; 83(17): 10398-10408, 2018 09 07.
Artigo em Inglês | MEDLINE | ID: mdl-30102032

RESUMO

meta-Phenylene bis(phenylurea) receptors 1-4 were designed and synthesized to investigate the association between receptor shape, anion-selective binding and anion-directed self-assembly processes. Solution studies, performed through 1H NMR titrations with a variety of tetra- N-butylammonium salts, demonstrated strong binding of 2 equiv of H2PO4-, AcO-, BzO- anions and comparatively weak binding of Cl-, HSO4-, and SO42- anions. Binding modes and stability constants (log ß) were determined by regression analysis of the obtained 1H NMR titration data in DMSO- d6, and the cooperativities of the binding interactions were probed. Host-guest complexes of receptors 1 and 2 were studied in the crystalline phase to further probe the anion-binding behavior of this motif. This included a triple-stranded helicate consisting of three strands of receptor 2 arranged around a mixed-phosphate anionic core, which was characterized by using X-ray crystallography.

15.
Dalton Trans ; 47(35): 12308-12317, 2018 Sep 11.
Artigo em Inglês | MEDLINE | ID: mdl-30113616

RESUMO

Chiral lanthanide-based supramolecular structures have gained significant importance in view of their application in imaging, sensing and other functional purposes. We have designed chiral C2-symmetrical ligands (L) based on the use of two 2,6-pyridine-dicarboxylic-amide moieties (pda), that differ from one another by the nature of the diamine spacer groups (from 1,3-phenylenedimethanamine (1(S,S), 2(R,R)) and benzene-1,3-diamine (3(S,S), 4(R,R)) to much bulkier 4,4'-(cyclohexane-1,1-diyl)bis(2,6-dimethylaniline) (5(S,S), 6(R,R))) between these two pda units. The self-assembly between L and Eu(iii) ions were investigated in CH3CN solution at low concentration whereby the changes in the absorbance, fluorescence and Eu(iii)-centred emission spectra allowed us to model the binding equilibria occurring in the solution to the presence of [Eu:L2], [Eu2:L2], [Eu2:L3] assemblies and reveal their high binding constant values. The self-assembly in solution were also studied at higher concentration by following the changes in the 1H NMR spectra of the ligands upon Eu(iii) addition, as well as by using MALDI-MS of the isolated solid state complexes. The chiroptical properties of the ligands were used in order to study the structural changes upon self-assembly between the ligands and Eu(iii) ions using circular dichroism (CD) and circularly polarised luminescence (CPL) spectroscopies. The photophysical properties of [Eu2:L3] complexes were evaluated in solution and showed a decrease of luminescence quantum yield when going from the ligand with smaller (1(S,S)) to bulkier (5(S,S)) linker from ∼5.8% to ∼2.6%. While mass-spectrometry revealed the possible formation of trinucler assemblies such as [Eu3:L3] and [Eu3:L2].

16.
Dalton Trans ; 47(30): 10080-10092, 2018 Jul 31.
Artigo em Inglês | MEDLINE | ID: mdl-29999051

RESUMO

The first examples of crystalline coordination polymers containing the tetraarylpyrrolo[3,2-b]pyrrole (TPP) fluorophore are presented. We have prepared three new TPP ligands L1, H2L2 and H2L3, containing nitrile, carboxylate and mixed imidazole-carboxylate donor functionality, respectively. The ligands themselves each show significant fluorescence in the solution phase, with the nitrile species exhibiting solvatofluorochromism and the two carboxylate-containing compounds exhibiting concentration-dependent emission colour suggesting aggregation processes in solution. Three 3-dimensional polymeric structures are then presented. The compound poly-[AgL12]SbF6·3THF·2H2O 1 is an eightfold-interpenetrated diamondoid material, while poly-[Zn4O(L2)3]·20DMA·10H2O 2 is a porous Metal-Organic Framework with pcu topology, and both 1 and 2 show notable luminescence in the solid state. Complex 2 readily undergoes guest exchange accompanied by a reversible switching in emission colour with no change in chemical structure. While complex poly-[CdL3]·2.5DMA·3.5H2O 3 is non-emissive, it displays a twofold interpenetrated pts topology with hexagonal symmetry and an extremely long hexagonal pitch of 100.3 Å, and shows an impressive 22 wt% CO2 uptake capacity at 278 K and 1 bar.

17.
Chem Sci ; 9(23): 5233-5241, 2018 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-29997878

RESUMO

Phenylalanine functionalised norbornene (9:Na) functions as a potent, low molecular-mass (MW = 333 Da) ionic organogelator with a minimum gelating concentration of 0.5 wt% in THF, i-PrOH, 1,4-dioxane and n-BuOH. Fibrous crystals form in the gel and X-ray crystallography identified a cation mediated helical assembly process controlled by the chirality of the phenylalanine. In addition to excellent gelating properties 9:Na readily forms aqueous biphasic and triphasic systems.

18.
Chem Commun (Camb) ; 54(33): 4120-4123, 2018 Apr 19.
Artigo em Inglês | MEDLINE | ID: mdl-29623325

RESUMO

The synthesis, photophysics and biological investigation of fluorescent 4-amino-1,8-naphthalimide Tröger's bases (TB-1-TB-3) and a new Tröger's base p-cymene-Ru(ii)-curcumin organometallic conjugate (TB-Ru-Cur) are described; these compounds showed fast cellular uptake and displayed good luminescence and cytotoxicity against cervical cancer cells.

19.
Chem Soc Rev ; 47(7): 2228-2248, 2018 Apr 03.
Artigo em Inglês | MEDLINE | ID: mdl-29493684

RESUMO

The field of molecular logic gates originated 25 years ago, when A. P. de Silva published a seminal article in Nature. Stimulated by this ground breaking research, scientists were inspired to join the race to simulate the workings of the fundamental components of integrated circuits using molecules. The rules of this game of mimicry were flexible, and have evolved and morphed over the years. This tutorial review takes a look back on and provides an overview of the birth and growth of the field of molecular logics. Spinning-off from chemosensor research, molecular logic gates quickly proved themselves to be more than intellectual exercises and are now poised for many potential practical applications. The ultimate goal of this vein of research became clearer only recently - to "boldly go where no silicon-based logic gate has gone before" and seek out a new deeper understanding of life inside tissues and cells.


Assuntos
Computadores Moleculares/tendências , Lógica , Humanos , Peróxido de Hidrogênio/análise , Mercúrio/análise , Estrutura Molecular , Imagem Óptica
20.
Dalton Trans ; 47(15): 5259-5268, 2018 Apr 17.
Artigo em Inglês | MEDLINE | ID: mdl-29565082

RESUMO

Flexible benzene-1,3,5-tricarboxamides (BTAs), organic species well-known for their tendencies to form functional soft-materials by virtue of their complementary hydrogen bonding, are explored as structurally reinforcing supramolecular building blocks in porous coordination polymers. We report the synthesis and characterisation of two related, carboxylate-terminated BTA derivatives, and the structure and functionality of their polymeric Cd(ii) complexes. The polycarboxylate ligand benzene-1,3,5-tricarboxamide tris(phenylacetic acid) H3L1 was prepared, and the analogous trimethyl benzene-1,3,5-tricarboxamide tris acetate Me3L2 was prepared and its single crystal structure elucidated. On reaction with cadmium nitrate in a DMF/H2O mixture, each BTA compound yielded coordination polymer species with columnar packing motifs comparable to the familiar BTA triple helix seen in purely organic systems. In the case of Me3L2, this transformation was achieved through a convenient in situ ester hydrolysis. Complex 1 is a 2-dimensional layered material containing tubular intralayer pores, in which amide-amide hydrogen bonding is a notable structural feature. In contrast, the structure of 2 contains no amide-amide hydrogen bonding, and instead a columnar arrangement of ligand species is linked by trinuclear Cd(ii) cluster nodes into a densely packed three-dimensional framework. The crystal structures revealed both materials exhibited significant solvent-accessible volume, and this was probed with thermal analysis and CO2 and N2 adsorption experiments; complex 2 showed negligible gas uptake, while compound 1 possesses an unusually high CO2 capacity for a two-dimensional material with intralayer porosity and surprising structural resilience to guest exchange, evacuation and exposure to air.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA