Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 1.887
Filtrar
Mais filtros

Intervalo de ano de publicação
1.
Proc Natl Acad Sci U S A ; 120(9): e2209924120, 2023 02 28.
Artigo em Inglês | MEDLINE | ID: mdl-36802431

RESUMO

Simultaneous poisoning by carbon monoxide (CO) and hydrogen cyanide is the major cause of mortality in fire gas accidents. Here, we report on the invention of an injectable antidote against CO and cyanide (CN-) mixed poisoning. The solution contains four compounds: iron(III)porphyrin (FeIIITPPS, F), two methyl-ß-cyclodextrin (CD) dimers linked by pyridine (Py3CD, P) and imidazole (Im3CD, I), and a reducing agent (Na2S2O4, S). When these compounds are dissolved in saline, the solution contains two synthetic heme models including a complex of F with P (hemoCD-P) and another one of F with I (hemoCD-I), both in their iron(II) state. hemoCD-P is stable in its iron(II) state and captures CO more strongly than native hemoproteins, while hemoCD-I is readily autoxidized to its iron(III) state to scavenge CN- once injected into blood circulation. The mixed solution (hemoCD-Twins) exhibited remarkable protective effects against acute CO and CN- mixed poisoning in mice (~85% survival vs. 0% controls). In a model using rats, exposure to CO and CN- resulted in a significant decrease in heart rate and blood pressure, which were restored by hemoCD-Twins in association with decreased CO and CN- levels in blood. Pharmacokinetic data revealed a fast urinary excretion of hemoCD-Twins with an elimination half-life of 47 min. Finally, to simulate a fire accident and translate our findings to a real-life scenario, we confirmed that combustion gas from acrylic cloth caused severe toxicity to mice and that injection of hemoCD-Twins significantly improved the survival rate, leading to a rapid recovery from the physical incapacitation.


Assuntos
Monóxido de Carbono , Porfirinas , Ratos , Camundongos , Animais , Antídotos/farmacologia , Oxigênio , Compostos Férricos , Cianetos/toxicidade , Ferro , Compostos Ferrosos
2.
Proc Natl Acad Sci U S A ; 119(20): e2122063119, 2022 05 17.
Artigo em Inglês | MEDLINE | ID: mdl-35533271

RESUMO

SignificanceThe chemical reduction of unsaturated bonds occurs by hydrogenation with H2 as the reductant. Conversely, in biology, the unavailability of H2 engenders the typical reduction of unsaturated bonds with electrons and protons from different cofactors, requiring olefin hydrogenation to occur by proton-coupled electron transfer (PCET). Moreover, the redox noninnocence of tetrapyrrole macrocycles furnishes unusual PCET intermediates, including the phlorin, which is an intermediate in tetrapyrrole ring reductions. Whereas the phlorin of a porphyrin is well established, the phlorin of a chlorin is enigmatic. By controlling the PCET reactivity of a chlorin, including the use of a hangman functionality to manage the proton transfer, the formation of a chlorinphlorin by PCET is realized, and the mechanism for its formation is defined.

3.
Nano Lett ; 24(1): 180-186, 2024 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-38150551

RESUMO

We investigated the Kondo effect of cobalt(II)-5-15-bis(4'-bromophenyl)-10,20-bis(4'-iodophenyl)porphyrin (CoTPPBr2I2) molecules on Au(111) with low-temperature scanning tunneling microscopy under ultrahigh vacuum conditions. The molecules exhibit four adsorption configurations at the top and bridge sites of the surface with different molecular orientations. The Kondo resonance shows extraordinary sensitivity to the adsorption configuration. By switching the molecule between different configurations, the Kondo temperature is varied over a wide range from ≈8 up to ≈250 K. Density functional theory calculations reveal that changes of the adsorption configuration lead to distinct variations of the hybridization between the molecule and the surface. Furthermore, we show that surface reconstruction plays a significant role for the molecular Kondo effect.

4.
Nano Lett ; 24(40): 12522-12528, 2024 Oct 09.
Artigo em Inglês | MEDLINE | ID: mdl-39349980

RESUMO

Functionalized porphyrins by introducing exotic atoms into their central cavities have significant applications across various fields. As unique nanographenes, porphyrins functionalized with monoboron are intriguing, yet their synthesis remains highly challenging. Herein, we present the first on-surface boronation of porphyrin, bonding a single boron atom into the porphyrin's cavity. The boronation is selective, being observed exclusively in molecules featuring a specific aromatic ring-fused structure (ARFS*), not the pristine porphyrin molecule or its other ARFS forms. The boron's bonding geometry is noncentered, transforming the boronated porphyrin into a molecular dipole and imparting a markedly varied electronic structure. Well-ordered two-dimensional dipole arrays are achieved. Upon elevated thermoactivation, intermolecular O-B-O bonds provide robustness and flexibility to the molecular chains. This work demonstrates the high selectivity of on-surface porphyrin boronation and provides an effective strategy for tailoring molecules' electronic structure, producing molecular dipoles, and promoting the robustness and flexibility of molecular chains.

5.
J Bacteriol ; 206(6): e0044423, 2024 06 20.
Artigo em Inglês | MEDLINE | ID: mdl-38506530

RESUMO

Cellular life relies on enzymes that require metals, which must be acquired from extracellular sources. Bacteria utilize surface and secreted proteins to acquire such valuable nutrients from their environment. These include the cargo proteins of the type eleven secretion system (T11SS), which have been connected to host specificity, metal homeostasis, and nutritional immunity evasion. This Sec-dependent, Gram-negative secretion system is encoded by organisms throughout the phylum Proteobacteria, including human pathogens Neisseria meningitidis, Proteus mirabilis, Acinetobacter baumannii, and Haemophilus influenzae. Experimentally verified T11SS-dependent cargo include transferrin-binding protein B (TbpB), the hemophilin homologs heme receptor protein C (HrpC), hemophilin A (HphA), the immune evasion protein factor-H binding protein (fHbp), and the host symbiosis factor nematode intestinal localization protein C (NilC). Here, we examined the specificity of T11SS systems for their cognate cargo proteins using taxonomically distributed homolog pairs of T11SS and hemophilin cargo and explored the ligand binding ability of those hemophilin cargo homologs. In vivo expression in Escherichia coli of hemophilin homologs revealed that each is secreted in a specific manner by its cognate T11SS protein. Sequence analysis and structural modeling suggest that all hemophilin homologs share an N-terminal ligand-binding domain with the same topology as the ligand-binding domains of the Haemophilus haemolyticus heme binding protein (Hpl) and HphA. We term this signature feature of this group of proteins the hemophilin ligand-binding domain. Network analysis of hemophilin homologs revealed five subclusters and representatives from four of these showed variable heme-binding activities, which, combined with sequence-structure variation, suggests that hemophilins are diversifying in function.IMPORTANCEThe secreted protein hemophilin and its homologs contribute to the survival of several bacterial symbionts within their respective host environments. Here, we compared taxonomically diverse hemophilin homologs and their paired Type 11 secretion systems (T11SS) to determine if heme binding and T11SS secretion are conserved characteristics of this family. We establish the existence of divergent hemophilin sub-families and describe structural features that contribute to distinct ligand-binding behaviors. Furthermore, we demonstrate that T11SS are specific for their cognate hemophilin family cargo proteins. Our work establishes that hemophilin homolog-T11SS pairs are diverging from each other, potentially evolving into novel ligand acquisition systems that provide competitive benefits in host niches.


Assuntos
Proteínas de Bactérias , Heme , Proteínas de Bactérias/metabolismo , Proteínas de Bactérias/genética , Proteínas de Bactérias/química , Heme/metabolismo , Proteínas Ligantes de Grupo Heme/metabolismo , Hemeproteínas/metabolismo , Hemeproteínas/genética , Hemeproteínas/química , Ligação Proteica , Proteobactérias/metabolismo , Proteobactérias/genética
6.
J Biol Chem ; 299(5): 104648, 2023 05.
Artigo em Inglês | MEDLINE | ID: mdl-36965616

RESUMO

IsdG-type enzymes catalyze the noncanonical degradation of heme to iron, staphylobilin (SB), and formaldehyde (HCHO), presumably by binding heme in an unusually distorted conformation. Their unique mechanism has been elucidated for MhuD from Mycobacterium tuberculosis, revealing an unusual ring opening of hydroxyheme by dioxygenation. A similar mechanism has been postulated for other IsdG enzymes; however, MhuD, which is special as an IsdG-type enzyme, retains a formyl group in the linearized tetrapyrrole. Recent reports on Staphylococcus aureus IsdG have suggested the formation of SB retaining a formyl group (formyl-SB), but its identification is preliminary. Furthermore, the reaction properties of formyl-SB and the mechanism of HCHO release remain unclear. In this study, the complex reaction of S. aureus IsdG was reexamined to elucidate its mechanism, including the identification of reaction products and their control mechanisms. Depending on the reaction conditions, IsdG produced both SB and formyl-SB as the main product, the latter of which was isolated and characterized by MS and NMR measurements. The formyl-SB product was generated upon the reaction between hydroxyheme-IsdG and O2 without reduction, indicating the dioxygenation mechanism as found for MhuD. Under reducing conditions, hydroxyheme-IsdG was converted also to SB and HCHO by activating another O2 molecule. These results provide the first overview of the complicated IsdG reaction. The heme distortion in the IsdG-type enzymes is shown to generally promote ring cleavage by dioxygenation. The presence or absence of HCHO release can be influenced by many factors, and the direct identification of S. aureus heme catabolites is of interest.


Assuntos
Formaldeído , Heme Oxigenase (Desciclizante) , Heme , Staphylococcus aureus , Catálise , Formaldeído/metabolismo , Heme/metabolismo , Heme Oxigenase (Desciclizante)/metabolismo , Staphylococcus aureus/enzimologia , Mycobacterium tuberculosis/metabolismo
7.
Small ; : e2406621, 2024 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-39344540

RESUMO

Photo-responsive adsorption has emerged as a vibrant area because it provides a promising route to reduce the energy consumption of the traditional adsorption separation. However, the current methodology to fabricate photo-responsive sorbents is still subject to the photo-deforming molecular units. In this study, a new initiative of photo-dissociated electron-hole pairs is proposed to generate amazing adsorption activity, and prove its feasibility. Employing CuPP [PP = 5,10,15,20-tetrakis(4-carboxyphenyl)porphyrin] framework nanosheets compounded with graphene, binary film (BF) sorbents are successfully fabricated. The paradigmatic BF nanostructure brings about efficiently photo-excited electron-hole pairs with durable enough lifetime to meet the needs of microscopic adsorption equilibrium, which ultimately alters the electron density distribution of adsorption surface, and thus markedly modulates the adsorption activity. Therefore, an amazing photo-enhanced adsorption capability for the index gas CO can be gotten. Once exposed to the visible-light at 420 nm, the CO adsorption capacity (0 °C, 1 bar) is risen from 0.23 mmol g-1 in the darkness to 1.66 mmol g-1, changed by + 622%. This is essentially different from majority of current photo-responsive sorbents based on photo-deforming molecular units, of which adsorption capability is only decreased with photo-induction, and the maximum rate of change reported is just -54%.

8.
Small ; 20(42): e2401117, 2024 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-39031811

RESUMO

Surface-enhanced Raman scattering (SERS) imaging integrating photothermal and photodynamic therapy (PTT/PDT) is a promising approach for achieving accurate diagnosis and effective treatment of cancers. However, most available Raman reporters show multiple signals in the fingerprint region, which overlap with background signals from cellular biomolecules. Herein, a 4T1 cell membrane-enveloped gold nanorods-manganese porphyrins system (GMCMs) is designed and successfully fabricated as a biomimetic theranostic nanoplatform. Manganese porphyrins are adsorbed on the surface of Au nanorods via the terminal alkynyl group. Cell membrane encapsulation protects the manganese porphyrins from falling off the gold nanorods. The biomimetic GMCMs confirm specific homologous targeting to 4T1 cells with good dispersibility, excellent photoacoustic (PA) imaging properties, and preferable photothermal and 1O2 generation performance. GMCMs exhibit distinct SERS signals in the silent region without endogenous biomolecule interference both in vitro and in vivo. Manganese ions could not only quench the fluorescence of porphyrins to enhance the SERS imaging effect but also deplete cellular GSH to increase 1O2 yield. Both in vitro and in vivo studies demonstrate that GMCMs effectively eradicate tumors through SERS/PA imaging-guided PTT/PDT. This study provides a feasible strategy for augmenting the Raman imaging effects of the alkynyl group and integrating GSH-depletion to enhance PTT/PDT efficacy.


Assuntos
Ouro , Manganês , Nanotubos , Técnicas Fotoacústicas , Fotoquimioterapia , Porfirinas , Análise Espectral Raman , Ouro/química , Fotoquimioterapia/métodos , Manganês/química , Nanotubos/química , Porfirinas/química , Porfirinas/uso terapêutico , Técnicas Fotoacústicas/métodos , Animais , Linhagem Celular Tumoral , Camundongos , Biomimética/métodos , Materiais Biomiméticos/química
9.
Small ; : e2402956, 2024 Oct 22.
Artigo em Inglês | MEDLINE | ID: mdl-39439186

RESUMO

The hypoxic condition in solid tumors induces therapy resistance, limited therapeutic efficacy, and tumor recurrence, especially for chemotherapy and aerobic photodynamic therapy (PDT). To address this matter, an O2 regulator (SNP@Ato) is designed for breaking chemoresistance and enhancing PDT, which is constructed by loading Atovaquone (Ato) through self-assembly and host-guest interaction between ß-cyclodextrin functionalized tetraphenylporphyrin (TPP-CD4) and thioketal-linked camptothecin/azobenzene (Azo-TK-CPT). Specifically, the porphyrin units in SNP@Ato are in "Off state" due to the photoinduced electron transfer (PET) effect between the porphyrin units and azobenzene. After encountering the hypoxic condition in solid tumors, SNP@Ato is dissociated by the cleaved azobenzene on account of over-expressed azo-reductase. Then the mitochondrial respiratory of cancer cells would be suppressed with the participation of Ato, generating a local hypoxia relief for sensitized chemotherapy and enhanced PDT. Accompanied by efficient PDT, the TK linker is broken by ROS, and the CPT is released from the prodrugs. Compared with the SNP group without oxygen-regulator, SNP@Ato exhibits a remarkable improvement of the therapeutic effect against hypoxic tumors in vitro and in vivo. This work proposes a novel paradigm for overcoming hypoxia-induced therapeutic resistance.

10.
Small ; 20(2): e2304998, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-37670222

RESUMO

Perturbation of the copper (Cu) active site by electron manipulation is a crucial factor in determining the activity and selectivity of electrochemical carbon dioxide (CO2 ) reduction reaction (e-CO2 RR) in Cu-based molecular catalysts. However, much ambiguity is present concerning their electronic structure-function relationships. Here, three molecular Cu-based porphyrin catalysts with different electron densities at the Cu active site, Cu tetrakis(4-methoxyphenyl)porphyrin (Cu─T(OMe)PP), Cu tetraphenylporphyrin (Cu─THPP), and Cu tetrakis(4-bromophenyl)porphyrin (Cu─TBrPP), are prepared. Although all three catalysts exhibit e-CO2 RR activity and the same reaction pathway, their performance is significantly affected by the electronic structure of the Cu site. Theoretical and experimental investigations verify that the conjugated effect of ─OCH3 and ─Br groups lowers the highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbitals (LUMO) gap of Cu─T(OMe)PP and Cu─TBrPP, promoting faster electron transfer between Cu and CO2 , thereby improving their e-CO2 RR activity. Moreover, the high inductive effect of ─Br group reduces the electron density of Cu active site of Cu─TBrPP, facilitating the hydrolysis of the bound H2 O and thus creating a preferable local microenvironment, further enhancing the catalytic performance. This work provides new insights into the relationships between the substituent group characteristics with e-CO2 RR performance and is highly instructive for the design of efficient Cu-based e-CO2 RR electrocatalysts.

11.
Small ; 20(36): e2310957, 2024 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-38698608

RESUMO

The efficacy of traditional radiotherapy (RT) has been severely limited by its significant side effects, as well as tumor hypoxia. Here, the nanoscale cerium (Ce)-based metaloxo clusters (Ce(IV)6)-porphyrin (meso-tetra (4-carboxyphenyl) porphyrin, TCPP) framework loaded with L-arginine (LA) (denoted as LA@Ce(IV)6-TCPP) is developed to serve as a multifarious radio enhancer to heighten X-ray absorption and energy transfer accompanied by O2/NO generation for hypoxia-improved RT-radiodynamic therapy (RDT) and gas therapy. Within tumor cells, LA@Ce(IV)6-TCPP will first react with endogenous H2O2 and inducible NO synthase (iNOS) to produce O2 and NO to respectively increase the oxygen supply and reduce oxygen consumption, thus alleviating tumor hypoxia. Then upon X-ray irradiation, LA@Ce(IV)6-TCPP can significantly enhance hydroxyl radical (•OH) generation from Ce(IV)6 metaloxo clusters for RT and synchronously facilitate singlet oxygen (1O2) generation from adjacently-coordinated TCPP for RDT. Moreover, both the •OH and 1O2 can further react with NO to generate more toxic peroxynitrite anions (ONOO-) to inhibit tumor growth for gas therapy. Benefitting from the alleviation of tumor hypoxia and intensified RT-RDT synergized with gas therapy, LA@Ce(IV)6-TCPP elicited superior anticancer outcomes. This work provides an effective RT strategy by using low doses of X-rays to intensify tumor suppression yet reduce systemic toxicity.


Assuntos
Cério , Óxido Nítrico , Oxigênio , Cério/química , Oxigênio/química , Óxido Nítrico/metabolismo , Óxido Nítrico/química , Animais , Porfirinas/química , Porfirinas/farmacologia , Linhagem Celular Tumoral , Humanos , Metaloporfirinas/química , Metaloporfirinas/farmacologia , Camundongos , Metais Terras Raras/química , Radioterapia/métodos , Gases/química , Arginina/química , Arginina/farmacologia
12.
Small ; : e2402779, 2024 Jul 31.
Artigo em Inglês | MEDLINE | ID: mdl-39082205

RESUMO

Rationally designing photocatalysts is crucial for the solar-driven nitrogen reduction reaction (NRR) due to the stable N≡N triple bond. Metal-organic frameworks (MOFs) are considered promising candidates but suffer from insufficient active sites and inferior charge transport. Herein, it is demonstrated that incorporating 3d metal ions, such as zinc (Zn) or iron (Fe) ions, into Al-coordinated porphyrin MOFs (Al-PMOFs) enables the enhanced ammonia yield of 88.7 and 65.0 µg gcat -1 h-1, 2.5- and 1.8-fold increase compared to the pristine Al-PMOF (35.4 µg gcat -1 h-1), respectively. The origin of ammonia (NH3) is verified via isotopic labeling experiments. Incorporating Zn or Fe into Al-PMOF generates active sites in Al-PMOF, that is, Zn-N4 or Fe-N4 sites, which not only facilitates the adsorption and activation of N2 molecules but suppresses the charge recombination. Photophysical and theoretical studies further reveal the upshift of the lowest unoccupied molecular orbital (LUMO) level to a more energetic position upon inserting 3d metal ions (with a more significant shift in Zn than Fe). The promoted nitrogen activation, suppressed charge recombination, and more negative LUMO levels in Al-PMOF(3d metal) contribute to a higher photocatalytic activity than pristine Al-PMOF. This work provides a promising strategy for designing photocatalysts for efficient solar-to-chemical conversion.

13.
Small ; 20(32): e2400592, 2024 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-38501796

RESUMO

Here, the molecule-modified Cu-based array is first constructed as the self-supporting tandem catalyst for electrocatalytic CO2 reduction reaction (CO2RR) to C2 products. The modification of cuprous oxide nanowire array on copper mesh (Cu2O@CM) with cobalt(II) tetraphenylporphyrin (CoTPP) molecules is achieved via a simple liquid phase method. The systematical characterizations confirm that the formation of axial coordinated Co-O-Cu bond between Cu2O and CoTPP can significantly promote the dispersion of CoTPP molecules on Cu2O and the electrical properties of CoTPP-Cu2O@CM heterojunction array. Consequently, as compared to Cu2O@CM array, the optimized CoTPP-Cu2O@CM sample as electrocatalyst can realize the 2.08-fold C2 Faraday efficiency (73.2% vs 35.2%) and the 2.54-fold current density (‒52.9 vs ‒20.8 mA cm-2) at ‒1.1 V versus RHE in an H-cell. The comprehensive performance is superior to most of the reported Cu-based materials in the H-cell. Further study reveals that the CoTPP adsorption on Cu2O can restrain the hydrogen evolution reaction, improve the coverage of *CO intermediate, and maintain the existence of Cu(I) at low potential.

14.
Small ; : e2401273, 2024 Jul 03.
Artigo em Inglês | MEDLINE | ID: mdl-38958069

RESUMO

Acid-treated multi-walled carbon nanotube (MWCNT) covalently functionalized with cobalt triphenothiazine porphyrin (CoTriPTZ-OH) A3B type porphyrin, containing three phenothiazine moieties (represented as MWCNT-CoTriPTZ) is synthesized and characterized by various spectroscopic and microscopic techniques. The nanoconjugate, MWCNT-CoTriPTZ, exhibits a pair of distinct redox peaks due to the Co2+/Co3+ redox process in 0.1 M pH 7.0 phosphate buffer. Further, it electrocatalytically oxidizes hydrazine at a low overpotential with a high current. This property is advantageously utilized for the sensitive determination of hydrazine. The developed electrochemical sensor exhibits high sensitivity (0.99 µAµM-1cm-2), a low limit of detection (4.5 ppb), and a broad linear calibration range (0.1 µM to 3.0 mM) for the determination of hydrazine. Further, MWCNT-CoTriPTZ is exploited for hydrazine-assisted green hydrogen synthesis. The high efficiency of hydrazine oxidation is confirmed by the low onset potential (0.45 V (vs RHE)) and 0.60 V (vs RHE) at the current density of 10 mA.cm-2. MWCNT-CoTriPTZ displays a high current density (77.29 mA.cm-2) at 1.45 V (vs RHE).

15.
Chembiochem ; 25(9): e202400138, 2024 May 02.
Artigo em Inglês | MEDLINE | ID: mdl-38478375

RESUMO

A porphyrin-BODIPY dyad (P-BDP) was obtained through covalent bonding, featuring a two-segment design comprising a light-harvesting antenna system connected to an energy acceptor unit. The absorption spectrum of P-BDP resulted from an overlap of the individual spectra of its constituent parts, with the fluorescence emission of the BODIPY unit experiencing significant quenching (96 %) due to the presence of the porphyrin unit. Spectroscopic, computational, and redox investigations revealed a competition between photoinduced energy and electron transfer processes. The dyad demonstrated the capability to sensitize both singlet molecular oxygen and superoxide radical anions. Additionally, P-BDP effectively induced the photooxidation of L-tryptophan. In suspensions of Staphylococcus aureus cells, the dyad led to a reduction of over 3.5 log (99.99 %) in cell survival following 30 min of irradiation with green light. Photodynamic inactivation caused by P-BDP was also extended to the individual bacterium level, focusing on bacterial cells adhered to a surface. This dyad successfully achieved the total elimination of the bacteria upon 20 min of irradiation. Therefore, P-BDP presents an interesting photosensitizing structure that takes advantage of the light-harvesting antenna properties of the BODIPY unit combined with porphyrin, offering potential to enhance photoinactivation of bacteria.


Assuntos
Compostos de Boro , Fármacos Fotossensibilizantes , Porfirinas , Staphylococcus aureus , Compostos de Boro/química , Compostos de Boro/farmacologia , Fármacos Fotossensibilizantes/farmacologia , Fármacos Fotossensibilizantes/química , Staphylococcus aureus/efeitos dos fármacos , Porfirinas/química , Porfirinas/farmacologia , Oxigênio Singlete/metabolismo , Oxigênio Singlete/química , Luz , Estrutura Molecular
16.
Chemistry ; 30(46): e202401741, 2024 Aug 19.
Artigo em Inglês | MEDLINE | ID: mdl-38839573

RESUMO

Aromaticity and antiaromaticity are foundational principes in organic chemistry, regularly invoked to explain stability, structure, and magnetic and electronic properties. There are ongoing challenges in assigning molecules as aromatic or antiaromatic using optical spectroscopy. Here we report spectroelectrochemical and computational analyses of porphyrin (18π neutral, aromatic) and norcorrole (16π neutral, antiaromatic), and their oxidized (16π porphyrin dication) and reduced (norcorrole 18π dianion) forms. Our results show that while the visible spectra are characteristic of (anti)aromaticity consistent with Hückel's rules, the IR spectra are much less informative, owing to the relative rigidity of norcorrole. The results have implications for the assignment of (anti)aromaticity in both ground-state and time-resolved spectra.

17.
Chemistry ; 30(33): e202400180, 2024 Jun 12.
Artigo em Inglês | MEDLINE | ID: mdl-38606436

RESUMO

Porphyrins are excellent light-harvesting complexes. Presently they are unsuitable for photovoltaic applications, as their excellent light absorbance is compensated to a large extent by their poor transport properties, where most excitons are lost by recombination. Arranging porphyrins in regular, strongly bound, lattices of surface-anchored metal-organic frameworks (PP-SURMOFs) may facilitate charge carrier dissociation, but does not significantly enhance the conductive properties. In most cases, photogenerated excitons traverse undirected, Brownian motion through a hopping process, resulting in a substantial diffusion length to reach electrodes, leading to significant exciton loss through recombination. Here, we propose to guide exciton diffusion indirectly by an external electric field. We show that electric fields, even as strong as 1 V nm-1, do not affect the HOMO-LUMO gap of the porphyrins. However, fields of 0.1 V nm-1 and even less demonstrate a notable Stark effect, with slight band gap reductions, for some PP-SURMOFs. When applied as an electric field gradient, for instance, via the substrate, it creates a unidirectional hopping pathway for the excitons. Consequently, we expect a significant reduction of exciton diffusion length leading to increased utilization of photogenerated excitons as they reach the electrodes. This strategy holds promise for integrating photoactive molecules in photovoltaic and photocatalytic applications.

18.
Chemistry ; 30(35): e202401240, 2024 Jun 20.
Artigo em Inglês | MEDLINE | ID: mdl-38632105

RESUMO

A triply linked dicarbacorrole dimer (7) was synthesized from a new meso-meso singly linked dicarbacorrole dimer precursor (6) via an oxidative fusion reaction by 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) in the presence of trifluoromethanesulfonic acid (TfOH). Single crystal X-ray structure of 7 adopts a flat conformation with a length as ca. 15.946 Šand a width as 6.903 Å, which can be regarded as a short carbaporphyrinoid tape. Two coordinated Cu ions keeps the +3 oxidation state in 7, as confirmed by NMR spectroscopy, single crystal X-ray diffraction and X-ray photoelectron spectroscopy (XPS). This is in sharp contrast to the Osuka's triply linked tetrapyrrolic corrole dimers, where the inner 3NH form is not stable and thus can only act as a divalent ligand. Due to the non-aromatic nature of dicarbacorrole macrocycle, the largely decreased HOMO-LUMO gap and red-shifted absorption of 7 are best ascribed to the strong electronic interaction between two dipyrromethene-type chromophores. To our knowledge, this is the first fully fused carbaporphyrinoid dimer with ß-ß, meso-meso, ß-ß triply linkages prepared to date.

19.
Chemistry ; : e202402680, 2024 Aug 28.
Artigo em Inglês | MEDLINE | ID: mdl-39196603

RESUMO

This work reported "trinitarian" porphyrin nanobelts, contained hetero-trimetal ions. The high-resolution mass spectrometry and X-ray crystallography proved PNBNiCuPd consisting of three different bent porphyrin(2.1.2.1) metal complex moieties. The redox properties indicate porphyrin nanobelts demonstrate the multielectron donating and accepting properties, more than nine redox processes.

20.
Chemistry ; 30(6): e202302835, 2024 Jan 26.
Artigo em Inglês | MEDLINE | ID: mdl-38116892

RESUMO

We present the fabrication of a novel Starfruit-shaped metal-organic framework (SMOF) composed of zirconium and Tetra(4-carboxyphenyl)porphine linkers. The SMOF exhibits a unique morphology with edge-sharing two-dimensional (2D) nanosheet petals. Our investigation unravels a captivating transformation process, wherein three-dimensional (3D) shuttle-shaped MOFs form initially and subsequently evolve into 2D nanosheet-based SMOF structures. The distinct morphology of SMOF showcases superior catalytic activity in detoxifying G-type nerve agent and blister agent simulants, surpassing that of its 3D counterparts. This discovery of the 3D-to-2D transition growth pathway unlocks exciting opportunities for exploring novel strategies in advanced MOF nanostructure development, not only for catalysis but also for various other applications.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA