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1.
Angew Chem Int Ed Engl ; 60(17): 9379-9383, 2021 Apr 19.
Artigo em Inglês | MEDLINE | ID: mdl-33590640

RESUMO

Charge-recombination processes are critical for photovoltaic applications and should be suppressed for efficient charge transport. Here, we report that an applied magnetic field (0-1 T) can be used control the charge-recombination dynamics in an expanded rosarin-C60 complex. In the low magnetic field regime (<100 mT), the charge-recombination rate slows down due to hyperfine coupling, as inferred from transient absorption spectroscopic analyses. In contrast, in the high field regime, i.e., over 500 mT, the charge-recombination rate recovers and increases because the Δg mechanism facilitates spin conversion to a triplet charge-separated state (S to T0 ) that undergoes rapid charge-recombination to a localized rosarin triplet state. Therefore, we highlight the charge-recombination rate and the localized triplet state population can be modulated by the magnetic field in charge donor/acceptor non-covalent complexes.

2.
J Am Chem Soc ; 143(3): 1278-1283, 2021 01 27.
Artigo em Inglês | MEDLINE | ID: mdl-33428381

RESUMO

Deferasirox, ExJade, is an FDA-approved iron chelator used for the treatment of iron overload. In this work, we report several fluorescent deferasirox derivatives that display unique photophysical properties, i.e., aggregation-induced emission (AIE), excited state intramolecular proton transfer, charge transfer, and through-bond and through-space conjugation characteristics in aqueous media. Functionalization of the phenol units on the deferasirox scaffold afforded the fluorescent responsive pro-chelator ExPhos, which enabled the detection of the disease-based biomarker alkaline phosphatase (ALP). The diagnostic potential of these deferasirox derivatives was supported by bacterial biofilm studies.


Assuntos
Deferasirox/análogos & derivados , Corantes Fluorescentes/química , Fosfatase Alcalina/análise , Antibacterianos/farmacologia , Proteínas de Bactérias/análise , Biofilmes/efeitos dos fármacos , Biomarcadores/análise , Cefoperazona/farmacologia , Deferasirox/farmacologia , Deferasirox/efeitos da radiação , Corantes Fluorescentes/farmacologia , Corantes Fluorescentes/efeitos da radiação , Luz , Staphylococcus aureus Resistente à Meticilina/efeitos dos fármacos , Staphylococcus aureus Resistente à Meticilina/enzimologia , Staphylococcus aureus Resistente à Meticilina/fisiologia , Testes de Sensibilidade Microbiana , Microscopia Confocal , Microscopia de Fluorescência , Pseudomonas aeruginosa/efeitos dos fármacos , Pseudomonas aeruginosa/enzimologia , Pseudomonas aeruginosa/fisiologia , Sulbactam/farmacologia
3.
Chem Soc Rev ; 50(1): 9-38, 2021 Jan 07.
Artigo em Inglês | MEDLINE | ID: mdl-33169731

RESUMO

Indicator displacement assays (IDAs) offer a unique and innovative approach to molecular sensing. IDAs can facilitate the detection of a range of biologically/environmentally important species, provide a method for the detection of complex analytes or for the determination and discrimination of unknown sample mixtures. These attributes often cannot be achieved by traditional molecular sensors i.e. reaction-based sensors/chemosensors. The IDA pioneers Inouye, Shinkai, and Anslyn inspired researchers worldwide to develop various extensions of this idea. Since their early work, the field of indicator displacement assays has expanded to include: enantioselective indicator displacement assays (eIDAs), fluorescent indicator displacement assays (FIDAs), reaction-based indicator displacement assays (RIAs), DimerDye disassembly assays (DDAs), intramolecular indicator displacement assays (IIDAs), allosteric indicator displacement assay (AIDAs), mechanically controlled indicator displacement assays (MC-IDAs), and quencher displacement assays (QDAs). The simplicity of these IDAs, coupled with low cost, high sensitivity, and ability to carry out high-throughput automation analysis (i.e., sensing arrays) has led to their ubiquitous use in molecular sensing, alongside the other common approaches such as reaction-based sensors and chemosensors. In this review, we highlight the various design strategies that have been used to develop an IDA, including the design strategies for the newly reported extensions to these systems. To achieve this, we have divided this review into sections based on the target analyte, the importance of each analyte and then the reported IDA system is discussed. In addition, each section includes details on the benefit of the IDAs and perceived limitations for each system. We conclude this Tutorial Review by highlighting the current challenges associated with the development of new IDAs and suggest potential future avenues of research.

4.
Molecules ; 25(21)2020 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-33143109

RESUMO

The peroxidase activity of hemin-peptide complexes remains a potential factor in oxidative damage relevant to neurodegeneration. Here, we present the effect of temperature, ionic strength, and pH relevant to pathophysiological conditions on the dynamic equilibrium between high-spin and low-spin hemin-Aß40 constructs. This influence on peroxidase activity was also demonstrated using 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and dopamine (DA) oxidation rate analyses with increasing ratios of Aß16 and Aß40 (up to 100 equivalents). Interaction and reactivity studies of aggregated Aß40-hemin revealed enhanced peroxidase activity versus hemin alone. Comparison of the results obtained using Aß16 and Aß40 amyloid beta peptides revealed marked differences and provide insight into the potential effects of hemin-Aß on neurological disease progression.


Assuntos
Peptídeos beta-Amiloides/química , Benzotiazóis/química , Dopamina/química , Hemina/química , Fragmentos de Peptídeos/química , Peroxidases/química , Ácidos Sulfônicos/química , Humanos , Oxirredução
5.
Chem Commun (Camb) ; 56(69): 9994-9997, 2020 Aug 27.
Artigo em Inglês | MEDLINE | ID: mdl-32724979

RESUMO

The use of protonation to switch nonaromatic expanded porphyrins to their corresponding anti-aromatic forms has not been widely explored. Here, we show that free-base pyriamethyrin and dipyriamethyrin display nonaromatic character, as inferred from NMR spectroscopic analyses, their optical properties, and theoretical calculations. Addition of two protons extends the π - conjugation of these amethyrin analogues and yields formally anti-aromatic systems.

6.
Chem Soc Rev ; 49(12): 3726-3747, 2020 Jun 22.
Artigo em Inglês | MEDLINE | ID: mdl-32525153

RESUMO

Cancer is among the leading causes of death worldwide. Although a number of new treatment options have been developed in recent years, there remains a need for improved chemotherapies. The primary challenges facing new cancer drugs include: (1) improving patient quality of life, (2) overcoming drug resistance and (3) lowering reoccurrence rates. Major drawbacks of current chemotherapeutics arise from poor selectivity towards cancer cells, dose limiting toxicities, compliance-reducing side effects, and an inability to address resistance mechanisms. Chemotherapeutics that fail to achieve complete eradication of the disease can also lead to relapse and promote treatment resistance. New strategies to overcome these drawbacks include the use of transition metal chelators and ionophores to alter selectively the concentrations of iron, copper, and zinc in cancer cells. A number of metal chelators have successfully demonstrated cytotoxicity and targeted activity against drug-resistant cancer cells; several have proved effective against cancer stem cells, a significant cause of tumour reoccurrence. However, problems with formulation and targeting have been noted. Recent efforts have thus focused on the design of pro-chelators, inactive versions of chelators that are designed to be activated in the tumour. This is an appealing strategy that may potentially increase efficacy towards cancer-resistant malignant cells. This Tutorial Review summarizes recent progress involving transition metal chelators, pro-chelators, and ionophores as potential cancer chemotherapeutics. We will focus on the reported agents that are able to coordinate iron, copper, and zinc.


Assuntos
Quelantes/química , Ionóforos/química , Elementos de Transição/química , Antineoplásicos/química , Antineoplásicos/uso terapêutico , Complexos de Coordenação/química , Complexos de Coordenação/uso terapêutico , Humanos , Neoplasias/tratamento farmacológico
7.
Front Chem ; 8: 389, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32582623

RESUMO

Here, we report a new pentafluoropropanamido rhodamine fluorescent probe (ACS-HNE) that allows for the selective detection of neutrophil elastase (NE). ACS-HNE displayed high sensitivity, with a low limit of detection (<5.3 nM), and excellent selectivity toward elastase over other relevant biological analytes and enzymes. The comparatively poor solubility and cell permeability of neat ACS-HNE was improved by creating an ACS-HNE-albumin complex; this approach allowed for improvements in the in situ visualization of elastase activity in RAW 264.7 cells relative to ACS-HNE alone. The present study thus serves to demonstrate a simple universal strategy that may be used to overcome cell impermeability and solubility limitations, and to prepare probes suitable for the cellular imaging of enzymatic activity in vitro.

8.
Chem Soc Rev ; 49(10): 2886-2915, 2020 May 21.
Artigo em Inglês | MEDLINE | ID: mdl-32226991

RESUMO

Central nervous system (CNS) neurodegeneration is defined by a complex series of pathological processes that ultimately lead to death. The precise etiology of these disorders remains unknown. Recent efforts show that a mechanistic understanding of the malfunctions underpinning disease progression will prove requisite in developing new treatments and cures. Transition metals and lanthanide ions display unique characteristics (i.e., magnetism, radioactivity, and luminescence), often with biological relevance, allowing for direct application in CNS focused imaging modalities. These techniques include positron emission tomography (PET), single-photon emission computed tomography (SPECT), magnetic resonance imaging (MRI), and luminescent-based imaging (LumI). In this Tutorial Review, we have aimed to highlight the various metal-based imaging techniques developed in the effort to understand the pathophysiological processes associated with neurodegeneration. Each section has been divided so as to include an introduction to the particular imaging technique in question. This is then followed by a summary of key demonstrations that have enabled visualization of a specific neuropathological biomarker. These strategies have either exploited the high binding affinity of a receptor for its corresponding biomarker or a specific molecular transformation caused by a target species, all of which produce a concomitant change in diagnostic signal. Advantages and disadvantages of each method with perspectives on the utility of molecular imaging agents for understanding the complexities of neurodegenerative disease are discussed.


Assuntos
Complexos de Coordenação/química , Indicadores e Reagentes/química , Metais/química , Doenças Neurodegenerativas/diagnóstico por imagem , Elementos de Transição/química , Animais , Humanos , Imageamento por Ressonância Magnética , Tomografia por Emissão de Pósitrons , Tomografia Computadorizada de Emissão de Fóton Único
10.
Molecules ; 25(6)2020 Mar 23.
Artigo em Inglês | MEDLINE | ID: mdl-32210058

RESUMO

The reaction between dipyriamethyrin and copper(II) acetate [Cu(OAc)2] afforded what is, to our knowledge, the first transition metal-dipyriamethyrin complex. Molecular and electronic characterization of this binuclear Cu(II) complex via EPR, UV-vis, and single crystal X-ray diffraction analysis revealed marked differences between the present constructs and previously reported binuclear copper(II) hexaphyrin species. UV-vis titration analyses provided evidence for a homotropic positive allosteric effect, wherein the binuclear species is formed without significant intermediacy of a monomeric complex.


Assuntos
Complexos de Coordenação , Cobre/química , Modelos Moleculares , Complexos de Coordenação/síntese química , Complexos de Coordenação/química , Estrutura Molecular
11.
Chem ; 6(3): 703-724, 2020 Mar 12.
Artigo em Inglês | MEDLINE | ID: mdl-32201749

RESUMO

The complex etiology of neurodegeneration continues to stifle efforts to develop effective therapeutics. New agents elucidating key pathways causing neurodegeneration might serve to increase our understanding and potentially lead to improved treatments. Here, we demonstrate that a water-soluble manganese(II) texaphyrin (MMn) is a suitable magnetic resonance imaging (MRI) contrast agent for detecting larger amyloid beta constructs. The imaging potential of MMn was inferred on the basis of in vitro studies and in vivo detection in Alzheimer's disease C. elegans models via MRI and ICP-MS. In vitro antioxidant- and cellular-based assays provide support for the notion that this porphyrin analog shows promise as a therapeutic agent able to mitigate the oxidative and nitrative toxic effects considered causal in neurodegeneration. The present report marks the first elaboration of an MRI-active metalloantioxidant that confers diagnostic and therapeutic benefit in Alzheimer's disease models without conjugation of a radioisotope, targeting moiety, or therapeutic payload.

12.
Inorg Chem ; 59(1): 32-47, 2020 Jan 06.
Artigo em Inglês | MEDLINE | ID: mdl-31247875

RESUMO

Porphyrin and related pyrrole-containing macrocycles, collectively porphyrinoids, are versatile ligands that allow access to a multitude of coordination modes. Judicious modification of the porphyrin core as well as the pendant substituents has extended the coordination chemistry of porphyrinoids to include systems that are able to stabilize f-block element complexes with possible utility. This review focuses on our group's efforts to prepare expanded porphyrin and porphyrinogen ligands that can serve as tools to study and apply f-element metal coordination chemistry: it covers the background of the topic, selected syntheses, and application of these species in the chemical and medical sciences.

13.
J Am Chem Soc ; 141(44): 17867-17874, 2019 11 06.
Artigo em Inglês | MEDLINE | ID: mdl-31609114

RESUMO

Here we report the first series of in-plane thorium(IV), uranium(IV), and neptunium(IV) expanded porphyrin complexes. These actinide (An) complexes were synthesized using a hexa-aza porphyrin analogue, termed dipyriamethyrin, and the nonaqueous An(IV) precursors, ThCl4(DME)2, UCl4, and NpCl4(DME)2. The molecular and electronic structures of the ligand, each An(IV) complex, and a corresponding uranyl(VI) complex were characterized using nuclear magnetic resonance (NMR) and UV-vis spectroscopies as well as single-crystal X-ray diffraction analysis. Computational analyses of these complexes, coupled to their structural features, provide support for the conclusion that a greater degree of covalency in the ligand-cation orbital interactions arises as the early actinide series is traversed from Th(IV) to U(IV) and Np(IV). The axial ligands in the present An(IV) complexes proved labile, allowing for the electronic features of these complexes to be further modified.

14.
Chem Sci ; 10(21): 5596-5602, 2019 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-31293744

RESUMO

A new mixed hexaphyrin, pyrihexaphyrin (0.1.0.0.1.0) (1), was prepared via an acid catalyzed cyclization between 5,5'-(pyridine-2,6-diyl)bis(pyrrole-2-carbaldehyde) (2) and terpyrrole (3). This expanded porphyrin undergoes a ring contraction upon metallation with uranyl silylamide [UO2[N(SiMe3)2]2] under anaerobic conditions followed by purification over basic aluminum oxide exposed to air. The uranyl-contracted pyrihexaphyrin (0.0.0.0.1.0) complex (4) produced as a result contains a unique structural architecture and possesses a formally 22 π-electron globally aromatic periphery, as inferred from NMR spectroscopy, single crystal X-ray diffraction, and computational analyses. Support for the proposed contraction mechanism came from experimental data and DFT calculations. Proton NMR and mass spectroscopic analysis provided the first insight into expanded porphyrin-mediated activation of the uranyl dication (UO2 2+).

15.
J Am Chem Soc ; 141(11): 4749-4755, 2019 03 20.
Artigo em Inglês | MEDLINE | ID: mdl-30813734

RESUMO

Different pyridine dipyrrolate cages including cage-based dimers and polymers may be fabricated in a controlled manner from the same two starting materials, namely, an angular ligand 1 and Zn(acac)2, by changing the counter cation source. With tetrabutylammonium (TBA+) and dimethyl viologen (DMV2+), Cage-3 and Cage-5 are produced. In these cages, two ligands act as bridges and serve to connect together two cage subunits to produce higher order ensembles. In Cage-3 and Cage-5, the TBA+ and DMV2+ counter cations lie outside the cavities of the respective cages. This stands in contrast to what is seen with a previously reported system, Cage-1, wherein dimethylammonium (DMA+) counter cations reside within the cage cavity. When the counter cations are tetraethylammonium (TEA+) and bis(cyclopentadienyl) cobalt(III) (Cp2Co+), polymeric cage materials, PC-1 and PC-2, are formed, respectively. The counter cations thus serve not only to balance charge but also to tune the structural features as a whole. The organic cations used in the present study also act to modulate the further assembly of individual cages. The present cation-based tuning emerges as a new method for a fine-tuning of the multidimensional morphology of self-assembled inorganic materials.

17.
ACS Chem Neurosci ; 10(1): 155-167, 2019 01 16.
Artigo em Inglês | MEDLINE | ID: mdl-30372021

RESUMO

The discovery of acetylcholine and acetylcholinesterase provided the first insight into the intricacies of chemical signal transduction and neuronal communication. Further elucidation of the underlying mechanisms led to an attendant leveraging of this knowledge via the synthesis of new therapeutics designed to control aberrant biochemical processes. The central role of the cholinergic system within human memory and learning, as well as its implication in Alzheimer's disease, has made it a point of focus within the neuropharmacology and medicinal chemistry communities. This review is focused on donepezil and covers the background, synthetic routes, structure-activity relationships, binding interactions with acetylcholinesterase, pharmacokinetics and metabolism, efficacy, adverse effects, and historical importance of this leading therapeutic in the treatment of Alzheimer's disease and true Classic in Chemical Neuroscience.


Assuntos
Inibidores da Colinesterase/química , Inibidores da Colinesterase/uso terapêutico , Donepezila/química , Donepezila/uso terapêutico , Acetilcolinesterase/metabolismo , Doença de Alzheimer/tratamento farmacológico , Doença de Alzheimer/metabolismo , Animais , Inibidores da Colinesterase/farmacologia , Donepezila/farmacologia , Humanos , Degeneração Neural/tratamento farmacológico , Degeneração Neural/metabolismo , Relação Estrutura-Atividade
18.
Chem Sci ; 11(4): 1107-1113, 2019 Nov 27.
Artigo em Inglês | MEDLINE | ID: mdl-34084367

RESUMO

Herein, we report a protein-based hybridization strategy that exploits the host-guest chemistry of HSA (human serum albumin) to solubilize the otherwise cell impermeable ONOO- fluorescent probe Pinkment-OAc. Formation of a HSA/Pinkment-OAc supramolecular hybrid was confirmed by SAXS and solution-state analyses. This HSA/Pinkment-OAc hybrid provided an enhanced fluorescence response towards ONOO- versus Pinkment-OAc alone, as determined by in vitro experiments. The HSA/Pinkment-OAc hybrid was also evaluated in RAW 264.7 macrophages and HeLa cancer cell lines, which displayed an enhanced cell permeability enabling the detection of SIN-1 and LPS generated ONOO- and the in vivo imaging of acute inflammation in LPS-treated mice. A remarkable 5.6 fold (RAW 264.7), 8.7-fold (HeLa) and 2.7-fold increased response was seen relative to Pinkment-OAc alone at the cellular level and in vivo, respectively. We anticipate that HSA/fluorescent probe hybrids will soon become ubiquitous and routinely applied to overcome solubility issues associated with hydrophobic fluorescent imaging agents designed to detect disease related biomarkers.

19.
Chem Commun (Camb) ; 54(68): 9422-9425, 2018 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-30079408

RESUMO

A set of self-assembled tri- and tetrapodal metal coordination cage structures (cage-1 and cage-2, respectively) constructed from the uranyl dication (UO22+) and a dibenzoic acid functionalised cis-calix[4]pyrrole (1) are described. The inherent photochemical reactivity of the uranyl dication mediates the transformation of cage-1 to cage-2via the activation of molecular oxygen.

20.
J Org Chem ; 83(16): 9568-9570, 2018 08 17.
Artigo em Inglês | MEDLINE | ID: mdl-29927588

RESUMO

The controlled preparation of higher order oligopyrrolic species holds broad utility across the chemical and material sciences. Here, we describe the gram-scale synthesis of a bench-stable 5,5″-unsubstituted terpyrrole in excellent yield via a tandem Suzuki cross-coupling with in situ deprotection. The solution and solid-state stability as well as UV-vis, fluorescence, and single crystal X-ray diffraction structure are also detailed.


Assuntos
Pirróis/química , Pirróis/síntese química , Técnicas de Química Sintética , Estabilidade de Medicamentos
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