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1.
Small ; : e2400485, 2024 Apr 28.
Artigo em Inglês | MEDLINE | ID: mdl-38678502

RESUMO

8-oxoguanines (8-oxoG) in cells form compromised G-quadruplexes (GQs), which may vary GQ mediated gene regulations. By mimicking molecularly crowded cellular environment using 40% DMSO or sucrose, here it is found that oxidized human telomeric GQs have stabilities close to the wild-type (WT) GQs. Surprisingly, while WT GQs show negative formation cooperativity between a Pt(II) binder and molecularly crowded environment, positive cooperativity is observed for oxidized GQ formation. Single-molecule mechanical unfolding reveals that 8-oxoG sequence formed more diverse and flexible structures with faster folding/unfolding transition kinetics, which facilitates the Pt(II) ligand to bind the best-fit structures with positive cooperativity. These findings offer new understanding on structures and properties of oxidized G-rich species in crowded environments. They also provide insights into the design of better ligands to target oxidized G-rich structures formed under oxidative cell stress.

2.
Photochem Photobiol Sci ; 22(11): 2587-2597, 2023 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-37725299

RESUMO

Pt(II) complexes supported by chelating, multidentate ligands containing π-extended, planar phenanthridine (benzo[c]quinoline) donors (RLPtCl) exhibit a promising in vitro therapeutic index compared with phenanthriplatin, a leading preclinical anticancer complex containing a monodentate phenanthridine ligand. Here, we report evidence for non-specific interactions of CF3LPtCl with DNA through intercalation-mediated turn-on luminescence in O2-saturated aqueous buffer. Brief irradiation with visible light (490 nm) was also found to drastically increase the activity of CF3LPtCl, with photocytotoxicity increased up to 87% against a variety of human cancer cell lines. Mechanistic studies highlight significantly improved cellular uptake of CF3LPtCl compared with cisplatin, with localization in the nucleus and mitochondria triggering effective apoptosis. Photosensitization experiments with 1,3-diphenylisobenzofuran demonstrate that CF3LPtCl efficiently mediates the generation of singlet dioxygen (1O2), highlighting the potential of RLPtCl in photodynamic therapy.


Assuntos
Antineoplásicos , Platina , Humanos , Platina/química , Antineoplásicos/química , Ligantes , DNA/química , Fenantridinas/química , Fenantridinas/metabolismo
3.
Int J Mol Sci ; 24(17)2023 Aug 27.
Artigo em Inglês | MEDLINE | ID: mdl-37686109

RESUMO

We conducted the first comprehensive investigation on the impact of head group modifications on the anticancer activities of fatty-acid-like Pt(IV) prodrugs (FALPs), which are a class of platinum-based metallodrugs that target mitochondria. We created a small library of FALPs (1-9) with diverse head group modifications. The outcomes of our study demonstrate that hydrophilic modifications exclusively enhance the potency of these metallodrugs, whereas hydrophobic modifications significantly decrease their cytotoxicity. To further understand this interesting structure-activity relationship, we chose two representative FALPs (compounds 2 and 7) as model compounds: one (2) with a hydrophilic polyethylene glycol (PEG) head group, and the other (7) with a hydrophobic hydrocarbon modification of the same molecular weight. Using these FALPs, we conducted a targeted investigation on the mechanism of action. Our study revealed that compound 2, with hydrophilic modifications, exhibited remarkable penetration into cancer cells and mitochondria, leading to subsequent mitochondrial and DNA damage, and effectively eradicating cancer cells. In contrast, compound 7, with hydrophobic modifications, displayed a significantly lower uptake and weaker cellular responses. The collective results present a different perspective, indicating that increased hydrophobicity may not necessarily enhance cellular uptake as is conventionally believed. These findings provide valuable new insights into the fundamental principles of developing metallodrugs.


Assuntos
Pró-Fármacos , Pró-Fármacos/farmacologia , Ácidos Graxos , Relação Estrutura-Atividade , Mitocôndrias , Transporte Biológico , Platina/farmacologia
4.
Molecules ; 28(13)2023 Jun 22.
Artigo em Inglês | MEDLINE | ID: mdl-37446578

RESUMO

Although iron is essential for all forms of life, it is also potentially toxic to cells as the increased and unregulated iron uptake can catalyze the Fenton reaction to produce reactive oxygen species (ROS), leading to lipid peroxidation of membranes, oxidation of proteins, cleavage of DNA and even activation of apoptotic cell death pathways. We demonstrate that Fe(hinok)3 (hinok = 2-hydroxy-4-isopropyl-2,4,6-cycloheptatrien-1-one), a neutral Fe(III) complex with high lipophilicity is capable of bypassing the regulation of iron trafficking to disrupt cellular iron homeostasis; thus, harnessing remarkable anticancer activity against a panel of five different cell lines, including Pt-sensitive ovarian cancer cells (A2780; IC50 = 2.05 ± 0.90 µM or 1.20 µg/mL), Pt-resistant ovarian cancer cells (A2780cis; IC50 = 0.92 ± 0.73 µM or 0.50 µg/mL), ovarian cancer cells (SKOV-3; IC50 = 1.23 ± 0.01 µM or 0.67 µg/mL), breast cancer cells (MDA-MB-231; IC50 = 3.83 ± 0.12 µM or 2.0 µg/mL) and lung cancer cells (A549; IC50 = 1.50 ± 0.32 µM or 0.82 µg/mL). Of great significance is that Fe(hinok)3 exhibits unusual selectivity toward the normal HEK293 cells and the ability to overcome the Pt resistance in the Pt-resistant mutant ovarian cancer cells of A2780cis.


Assuntos
Antineoplásicos , Neoplasias Ovarianas , Humanos , Feminino , Antineoplásicos/farmacologia , Antineoplásicos/uso terapêutico , Linhagem Celular Tumoral , Compostos Férricos/farmacologia , Neoplasias Ovarianas/tratamento farmacológico , Células HEK293 , Ferro/farmacologia , Apoptose
5.
Bioconjug Chem ; 32(2): 311-317, 2021 02 17.
Artigo em Inglês | MEDLINE | ID: mdl-33475341

RESUMO

Cell motions such as migration and change in cellular morphology are essential activities for multicellular organism in response to environmental stimuli. These activities are a result of coordinated clustering/declustering of integrin molecules at the cell membrane. Here, we prepared DNA origami nanosprings to modulate cell motions by targeting the clustering of integrin molecules. Each nanospring was modified with arginyl-glycyl-aspartic acid (RGD) domains with a spacing such that when the nanospring is coiled, the RGD ligands trigger the clustering of integrin molecules, which changes cell motions. The coiling or uncoiling of the nanospring is controlled, respectively, by the formation or dissolution of an i-motif structure between neighboring piers in the DNA origami nanodevice. At slightly acidic pH (<6.5), the folding of the i-motif leads to the coiling of the nanospring, which inhibits the motion of HeLa cells. At neutrality (pH 7.4), the unfolding of the i-motif allows cells to resume mechanical movement as the nanospring becomes uncoiled. We anticipate that this pH-responsive DNA nanoassembly is valuable to inhibit the migration of metastatic cancer cells in acidic extracellular environment. Such a chemo-mechanical modulation provides a new mechanism for cells to mechanically respond to endogenous chemical cues.


Assuntos
Movimento Celular , DNA/química , Nanoestruturas/química , Células HeLa , Humanos , Concentração de Íons de Hidrogênio
6.
Inorganica Chim Acta ; 452: 125-129, 2016 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-27818526

RESUMO

The cellular response evoked by a hexanuclear platinum complex, Pt6L4 (1), is reported. Compound 1, a 3-nm octahedral cage formed by self-assembly of six Pt(II) centers and four 2,4,6-tris(4-pyridyl)-1,3,5-triazine ligands (L), exhibits promising in vitro potency against a panel of human cancer cell lines. Unlike classical platinum-based anticancer agents, 1 interacts with DNA in a non-covalent, intercalative manner and promotes DNA condensation. In cancer cells, 1 induces DNA damage, upregulates p53, its phosphorylated form phospho-p53 and its downstream effector, p21, as well as both apoptosis and senescence.

7.
J Am Chem Soc ; 137(47): 14854-7, 2015 Dec 02.
Artigo em Inglês | MEDLINE | ID: mdl-26561720

RESUMO

Expression of indoleamine-2,3-dioxygenase (IDO), an immunosuppressive enzyme in human tumors, leads to immune evasion and tumor tolerance. IDO is therefore a tumor immunotherapeutic target, and several IDO inhibitors are currently undergoing clinical trials. IDO inhibitors can enhance the efficacy of common cancer chemotherapeutics. Here we investigate Pt(IV)-(D)-1-methyltryptophan conjugates 1 and 2 for combined immunomodulation and DNA cross-link-triggered apoptosis for cancer "immuno-chemotherapy". Compound 2 effectively kills hormone-dependent, cisplatin-resistant human ovarian cancer cells, inhibiting IDO by transcriptional deregulation of the autocrine-signaling loop IDO-AHR-IL6, which blocks kynurenine production and promotes T-cell proliferation. Additionally, 1 and 2 display low toxicity in mice and are stable in blood. To our knowledge, this construct is the first Pt drug candidate with immune checkpoint blockade properties.


Assuntos
Antineoplásicos/uso terapêutico , Imunoterapia , Indolamina-Pirrol 2,3,-Dioxigenase/metabolismo , Neoplasias Ovarianas/terapia , Feminino , Humanos , Neoplasias Ovarianas/tratamento farmacológico
8.
J Am Chem Soc ; 137(8): 2967-74, 2015 Mar 04.
Artigo em Inglês | MEDLINE | ID: mdl-25698398

RESUMO

Rhenium(V) oxo complexes of general formula [ReO(OMe)(N^N)Cl2], where N^N = 4,7-diphenyl-1,10-phenanthroline, 1, or 3,4,7,8-tetramethyl-1,10-phenanthroline, 2, effectively kill cancer cells by triggering necroptosis, a non-apoptotic form of cell death. Both complexes evoke necrosome (RIP1-RIP3)-dependent intracellular reactive oxygen species (ROS) production and propidium iodide uptake. The complexes also induce mitochondrial membrane potential depletion, a possible downstream effect of ROS production. Apparently, 1 and 2 are the first rhenium complexes to evoke cellular events consistent with programmed necrosis in cancer cells. Furthermore, 1 and 2 display low acute toxicity in C57BL/6 mice and reasonable stability in fresh human blood.


Assuntos
Antineoplásicos/química , Antineoplásicos/farmacologia , Apoptose/efeitos dos fármacos , Compostos Organometálicos/química , Compostos Organometálicos/farmacologia , Fenantrolinas/química , Rênio/química , Animais , Antineoplásicos/síntese química , Antineoplásicos/toxicidade , Ciclo Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Estabilidade de Medicamentos , Humanos , Camundongos , Modelos Moleculares , Conformação Molecular , Necrose/induzido quimicamente , Compostos Organometálicos/síntese química , Compostos Organometálicos/toxicidade , Receptor PAR-1/metabolismo , Proteína Supressora de Tumor p53/metabolismo
9.
J Am Chem Soc ; 136(41): 14413-6, 2014 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-25247635

RESUMO

The effect of a newly developed osmium(VI) nitrido complex, 1, on breast cancer stem cells (CSCs) is reported. The complex displays selective toxicity for HMLER breast cancer cells enriched with CD44-positive, CSC-like cells over the same cells having reduced CSC character. Remarkably, 1 also reduces the proportion of CSCs within a heterogeneous breast cancer cell population and irreversibly inhibits the formation of free-floating mammospheres to an extent similar to that of salinomycin, a natural product that targets CSCs. Detailed mechanistic studies reveal that in breast cancer cells 1 induces DNA damage and endoplasmic reticulum stress, the latter being responsible for the CSC selectivity. The anti-CSC properties of 1 provide a strong impetus for the development of new metal-based compounds to target CSCs and to treat chemotherapy-resistant and relapsed tumors.


Assuntos
Antineoplásicos/farmacologia , Neoplasias da Mama/tratamento farmacológico , Complexos de Coordenação/farmacologia , Células-Tronco Neoplásicas/efeitos dos fármacos , Compostos de Nitrogênio/química , Osmio/química , Antineoplásicos/síntese química , Antineoplásicos/química , Neoplasias da Mama/patologia , Proliferação de Células/efeitos dos fármacos , Complexos de Coordenação/síntese química , Complexos de Coordenação/química , Relação Dose-Resposta a Droga , Ensaios de Seleção de Medicamentos Antitumorais , Humanos , Conformação Molecular , Células-Tronco Neoplásicas/patologia , Relação Estrutura-Atividade
10.
J Am Chem Soc ; 136(24): 8790-8, 2014 Jun 18.
Artigo em Inglês | MEDLINE | ID: mdl-24902769

RESUMO

Albumin is the most abundant protein in human serum and drugs that are administered intravenously inevitably interact with it. We present here a series of platinum(IV) prodrugs designed specifically to enhance interaction with human serum albumin (HSA) for drug delivery. This goal is achieved by asymmetrically functionalizing the axial ligands of the prodrug so as to mimic the overall features of a fatty acid. Systematic variation of the length of the aliphatic tail tunes the cellular uptake and, consequently, the cytotoxicity of cis,cis,trans-[Pt(NH3)2Cl2(O2CCH2CH2COOH)(OCONHR)], 4, where R is a linear alkyl group. Investigation of an analogue bearing a fluorophore conjugated to the succinate ligand confirmed that these compounds are reduced by biological reductants with loss of the axial ligands. Intracellular release of cisplatin from 4 was further confirmed by observing the characteristic effects of cisplatin on the cell cycle and morphology following treatment with the prodrug. The most potent member of series 4, for which R is a hexadecyl chain, interacts with HSA in a 1:1 stoichiometry to form the platinum-protein complex 7. The interaction is non-covalent and extraction with octanol completely removes the prodrug from an aqueous solution of HSA. Construct 7 is robust and can be isolated following fast protein liquid chromatography. The nature of the tight interaction was investigated computationally, and these studies suggest that the prodrug is buried below the surface of the protein. Consequently, complexation to HSA is able to reduce the rate of reduction of the prodrug by ascorbate. The lead compound from series 4 also exhibited significant stability in whole human blood, attributed to its interaction with HSA. This favorable redox profile, in conjunction with the established nonimmunogenicity, biocompatibility, and enhanced tumor accumulation of HSA, produces a system that holds significant therapeutic potential.


Assuntos
Sistemas de Liberação de Medicamentos , Desenho de Fármacos , Compostos Organoplatínicos/química , Pró-Fármacos/química , Albumina Sérica/química , Antineoplásicos/síntese química , Antineoplásicos/química , Antineoplásicos/farmacologia , Ciclo Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Relação Dose-Resposta a Droga , Ensaios de Seleção de Medicamentos Antitumorais , Humanos , Modelos Moleculares , Conformação Molecular , Compostos Organoplatínicos/síntese química , Compostos Organoplatínicos/farmacologia , Pró-Fármacos/síntese química , Pró-Fármacos/farmacologia , Relação Estrutura-Atividade
11.
Dalton Trans ; 53(7): 3206-3214, 2024 Feb 13.
Artigo em Inglês | MEDLINE | ID: mdl-38247554

RESUMO

Although iron is a bio-essential metal, dysregulated iron acquisition and metabolism result in production of reactive oxygen species (ROS) due to the Fenton catalytic reaction, which activates ferroptotic cell death pathways. The lipophilic Fe(III)-chelator chlorquinaldol (L; i.e., 5,7-dichloro-8-hydroxy-2-methylquinoline) strongly favors the formation of a highly stable binuclear Fe(III) complex [(L2Fe)2(µ-O)] (1) that can mimic the function of the Fe(III)-transferrin complex in terms of the strong binding to Fe(III) and facile release of Fe(II) when the metal center is reduced. It should be noted that the cellular uptake of 1 is not transferrin receptor-mediated but enhanced by the high lipophilicity of chlorquinaldol. Once 1 is transported across the cell membrane, Fe(III) can be reduced by ferric reductase or other cellular antioxidants to be released as Fe(II), which triggers the Fenton catalytic reaction, thus harnessing the anticancer activity of iron. As the result, this transferrin-inspired iron-delivery strategy significantly reduces the cytotoxicity of 1 in normal human embryonic kidney cells (HEK 293) and the hemolytic activity of 1 in human red blood cells (hRBCs), giving rise to the unique tumor-specific anticancer activity of this Fe(III) complex.


Assuntos
Clorquinaldol , Ferroptose , Humanos , Ferro/metabolismo , Transferrina/metabolismo , Clorquinaldol/metabolismo , Células HEK293 , Membrana Celular/metabolismo , Metais/metabolismo , Compostos Férricos/metabolismo , Compostos Ferrosos/metabolismo
12.
Curr Opin Chem Biol ; 73: 102276, 2023 04.
Artigo em Inglês | MEDLINE | ID: mdl-36878171

RESUMO

The rise of supramolecular chemistry offers new tools to design therapeutics and delivery platforms for biomedical applications. This review aims to highlight the recent developments that harness host-guest interactions and self-assembly to design novel supramolecular Pt complexes as anticancer agents and drug delivery systems. These complexes range from small host-guest structures to large metallosupramolecules and nanoparticles. These supramolecular complexes integrate the biological properties of Pt compounds and novel supramolecular structures, which inspires new designs of anticancer approaches that overcome problems in conventional Pt drugs. Based on the differences in Pt cores and supramolecular structures, this review focuses on five different types of supramolecular Pt complexes, and they include host-guest complexes of the FDA-approved Pt(II) drugs, supramolecular complexes of nonclassical Pt(II) metallodrugs, supramolecular complexes of fatty acid-like Pt(IV) prodrugs, self-assembled nanotherapeutics of Pt(IV) prodrugs, and self-assembled Pt-based metallosupramolecules.


Assuntos
Antineoplásicos , Neoplasias , Pró-Fármacos , Humanos , Pró-Fármacos/química , Pró-Fármacos/uso terapêutico , Platina/química , Sistemas de Liberação de Medicamentos , Antineoplásicos/farmacologia , Antineoplásicos/uso terapêutico , Neoplasias/tratamento farmacológico
13.
Dalton Trans ; 52(31): 10942-10950, 2023 Aug 08.
Artigo em Inglês | MEDLINE | ID: mdl-37490033

RESUMO

We hereby engineered photoactivatable Pt(IV) metallodrugs that harness CD36 to target ovarian cancer cells. Pt(IV) compounds mimic the structure of fatty acids and take advantage of CD36 as a "Trojan horse" to gain entry into the cells. We confirmed that CD36-dependent entry occurs using graphite furnace atomic absorption spectroscopy with ovarian cancer cells expressing different levels of CD36 and a CD36 inhibitor, SSO. Once the Pt(IV) metallodrugs enter the cancer cells, they can be activated to form Pt(II) with characteristics of cisplatin under visible light (490 nm) irradiation, promoting photoinduced electron transfer from the attached fluorophore to the metal center. This light-induced activation can increase the cytotoxicity of the Pt(IV) metallodrugs by up to 20 times toward ovarian cancer cells, inducing DNA damage and enabling efficient elimination of drug-resistant cancer cells.


Assuntos
Antineoplásicos , Neoplasias Ovarianas , Pró-Fármacos , Humanos , Feminino , Platina/química , Pró-Fármacos/farmacologia , Pró-Fármacos/química , Antineoplásicos/química , Compostos Organoplatínicos/farmacologia , Compostos Organoplatínicos/química , Cisplatino/farmacologia , Luz , Neoplasias Ovarianas/tratamento farmacológico , Linhagem Celular Tumoral
14.
Dalton Trans ; 51(5): 2012-2018, 2022 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-35029256

RESUMO

In this work, we present the first study about the interactions of mitochondria-damaging Pt(IV) prodrugs with cytochrome c. We synthesized a cisplatin-based Pt(IV) prodrug bearing a lipophilic hydrocarbon tail and anionic dansyl head group. The amphiphilic structure facilitates its accumulation in the mitochondria of cancer cells, which was validated using graphite furnace atomic absorption spectroscopy (GFAAS) and fluorescence imaging. Accordingly, this Pt(IV) prodrug is able to trigger mitochondrial damage and apoptosis. Overall, the Pt(IV) prodrug exhibits superior therapeutic effects against a panel of human cancer cells compared to cisplatin. It also overcomes drug resistance in ovarian cancer. Notably, HPLC analysis indicates that cytochrome c accelerates reduction (or activation) of the Pt(IV) prodrug in the presence of the electron donor nicotinamide adenine dinucleotide (NADH). More interestingly, additional studies indicate that cytochrome c was platinated by the reduced product of Pt(IV) prodrugs, and that empowers the proapoptotic peroxidase activity.


Assuntos
Antineoplásicos/farmacologia , Citocromos c/metabolismo , Mitocôndrias/efeitos dos fármacos , Compostos de Platina/farmacologia , Pró-Fármacos/farmacologia , Antineoplásicos/química , Linhagem Celular Tumoral , Cromatografia Líquida de Alta Pressão , Humanos , Pró-Fármacos/química
16.
J Am Chem Soc ; 133(42): 17045-55, 2011 Oct 26.
Artigo em Inglês | MEDLINE | ID: mdl-21973048

RESUMO

Post-self-assembly modifications of a discrete metal-organic supramolecular structure have been developed. Such modifications allow the properties of the self-assembled supramolecular species to be changed in a simple and efficient manner (>90% yield). Initiated by the application of chemical stimuli, the post-self-assembly modifications described herein result in three distinct changes to the supramolecular system: an individual building-block component change, an overall structural modification, and a functional evolution of a [6+4] metal-organic supramolecular structure. The three modifications have been carefully examined by a range of characterization methods, including NMR and UV-vis spectroscopy, electrospray ionization mass spectrometry, pulsed field gradient spin echo NMR measurements, electrochemical analysis, and computational simulations.


Assuntos
Compostos Organometálicos/química , Eletroquímica , Espectroscopia de Ressonância Magnética , Modelos Moleculares
17.
J Am Chem Soc ; 133(28): 10752-5, 2011 Jul 20.
Artigo em Inglês | MEDLINE | ID: mdl-21671637

RESUMO

The multicomponent coordination-driven self-assembly of hexakis[4-(4-pyridyl)phenyl]benzene, cis-(PEt(3))(2)Pt(II)(OTf)(2), and amine- or maleimide-functionalized isophthalate forms discrete hexagonal prisms as single reaction products. The amino or maleimide groups decorating the isophthalate pillars of the prisms provide reactive sites for post-self-asssembly modifications. In this communication, we demonstrate that the hexagonal prisms can be functionalized without disrupting the prismatic cores, enabling the incorporation of new functionalities under mild conditions.


Assuntos
Compostos Organometálicos/química , Platina/química , Aminas/química , Desenho de Fármacos , Maleimidas/química , Modelos Moleculares , Conformação Molecular
18.
Inorg Chem ; 50(13): 6107-13, 2011 Jul 04.
Artigo em Inglês | MEDLINE | ID: mdl-21634384

RESUMO

A new approach for the construction of functionalized metallosupramolecular tetragonal prisms via multicomponent, coordination-driven, template-free self-assembly is described. The combination of tetra-(4-pyridylphenyl)ethylene, a 90° Pt(II) acceptor, and ditopic bipyridine or carboxylate ligands functionalized with hydroxyl or amine groups, hydrophobic alkyl chains, or electrochemically active ferrocene, yields a suite of seven self-assembled tetragonal prisms under mild conditions. These three-dimensional metallosupramolecules were characterized by multinuclear NMR ((31)P and (1)H) and mass spectrometry. Their shapes and sizes were established using Merck Molecular Force Field (MMFF) simulations. In addition, their approximate sizes were further supported by pulsed-field-gradient spin-echo (PGSE) NMR experiments.


Assuntos
Compostos Organoplatínicos/síntese química , Platina/química , Substâncias Macromoleculares/química , Espectroscopia de Ressonância Magnética , Espectrometria de Massas , Modelos Moleculares , Estrutura Molecular , Compostos Organoplatínicos/química
19.
Inorg Chem ; 50(4): 1506-12, 2011 Feb 21.
Artigo em Inglês | MEDLINE | ID: mdl-21214171

RESUMO

The design and preparation of novel M(3)L(2) trigonal cages via the coordination-driven self-assembly of preorganized metalloligands containing octahedral aluminum(III), gallium(III), or ruthenium(II) centers is described. When tritopic or dinuclear linear metalloligands and appropriate complementary subunits are employed, M(3)L(2) trigonal-bipyramidal and trigonal-prismatic cages are self-assembled under mild conditions. These three-dimensional cages were characterized with multinuclear NMR spectroscopy ((1)H and (31)P) and high-resolution electrospray ionization mass spectrometry. The structure of one such trigonal-prismatic cage, self-assembled from an arene ruthenium metalloligand, was confirmed via single-crystal X-ray crystallography. The fluorescent nature of these prisms, due to the presence of their electron-rich ethynyl functionalities, prompted photophysical studies, which revealed that electron-deficient nitroaromatics are effective quenchers of the cages' emission. Excited-state charge transfer from the prisms to the nitroaromatic substrates can be used as the basis for the development of selective and discriminatory turn-off fluorescent sensors for nitroaromatics.


Assuntos
Hidrocarbonetos Aromáticos/química , Metais/química , Nitrocompostos/química , Compostos Organometálicos/química , Espectrometria de Fluorescência/métodos , Alumínio/química , Cristalografia por Raios X/métodos , Gálio/química , Ligantes , Rutênio/química , Espectrometria de Massas por Ionização por Electrospray/métodos
20.
Tetrahedron Lett ; 52(17): 2188-2191, 2011 Apr 27.
Artigo em Inglês | MEDLINE | ID: mdl-21516167

RESUMO

The design and synthesis of coordinative supramolecular polygons with open binding sites is described. Coordination-driven self-assembly of 2,6-bis(pyridin-4-ylethynyl)pyridine with 60° and 120° organoplatinum acceptors results in quantitative formation of a supramolecular rhomboid and hexagon, respectively, both bearing open pyridyl binding sites. The structures were determined by multinuclear ((31)P and (1)H) NMR spectroscopy and electrospray ionization (ESI) mass spectrometry, along with a computational study.

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