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1.
Yakugaku Zasshi ; 144(10): 911-918, 2024.
Artigo em Japonês | MEDLINE | ID: mdl-39358246

RESUMO

π-Extended donor-acceptor (D-A)-type molecules, which bear both electron-donor and electron-acceptor substituents on the backbone, exhibit unique optical properties, such as bathochromic shifts in absorption and emission, large Stokes shifts, solvatochromic behavior, and fluorescence quenching in polar solvents. These unique properties are attributed to intramolecular charge transfer (ICT) or twisted intramolecular charge transfer (TICT) in the ground and excited states. This review article introduces three types of D-A-type molecules that are used as detection reagents for (1) methanol, (2) amino acids during solid-phase peptide synthesis (SPPS), and (3) amines present in the biological environment. For methanol detection, D-A-type fluorophores with basic guanidine moieties were developed to differentiate between methanol (MeOH) and ethanol (EtOH) based on the small difference in their pKa values (ΔpKa=0.4). Selective protonation of the guanidine moiety in methanol disrupts the D-A structure, allowing emission in the resultant polar environment. Similarly, an acid-base reaction between the hydrogen chloride (HCl) salts of the D-A-type molecules and amines is applied to detect amines during SPPS. In this method, a colorless solution of an HCl salt of the D-A-type molecule is deprotonated by amines, forming a yellow solution. This is the first reported quantitative and non-destructive colorimetric method for detecting amines. Finally, a turn-on-type amine-labeling reagent was developed for the nucleophilic aromatic substitution (SNAr) reaction. This new reagent enables protein staining of living cells with a large Stokes shift and without solvent-polarity-dependent fluorescence quenching.


Assuntos
Aminas , Aminoácidos , Metanol , Aminoácidos/análise , Aminas/química , Técnicas de Síntese em Fase Sólida , Peptídeos , Corantes Fluorescentes , Indicadores e Reagentes , Guanidina/química , Etanol/análise
2.
Small ; : e2406723, 2024 Oct 02.
Artigo em Inglês | MEDLINE | ID: mdl-39358942

RESUMO

Conjugated microporous polymers (CMPs) are an important class of organic materials with several useful features like, inherent nanoscale porosity, large specific surface area and semiconducting properties, which are very demanding for various sustainable applications. Carbazole building blocks are extensively used in designing photocatalysts due to easy electron donation and hole transportation. In the current study, a new CMP material CBZ-CMP containing carbazole unit used for photocatalytic C═N coupling reaction under blue light irradiation is designed. The CBZ-CMP framework is made through the polycondensation of 4,4'-di(9H-carbazol-9-yl)-1,1'-biphenyl using FeCl3 as a catalyst. The CBZ-CMP shows very high BET surface area of 1536 m2 g-1 together with unimodal porosity (ca. 1.7 nm supermicropore), nanowire-like particle morphology (16-18 nm diameter), and low band gap property. The bi-phenyl moiety functions as the electron accepting center and the carbazole unit acts as the donor center, which accounts for the low band gap energy of CBZ-CMP. This nanoporous semiconducting CBZ-CMP material for photocatalytic benzylamine coupling reaction is explored, where it shows good conversion together with high selectivity under mild reaction conditions. This study offers simple method of preparation of a D-A-D-based porous photocatalyst for sustainable synthesis of value-added organics.

3.
J Colloid Interface Sci ; 678(Pt B): 955-969, 2024 Sep 07.
Artigo em Inglês | MEDLINE | ID: mdl-39270395

RESUMO

Constructing photocatalysts for the stable and efficient production of NH3 is of excellent research significance and challenging. In this paper, the electron acceptor 5-amino-1,10-phenanthroline (AP) is introduced into the electron-donor graphitic carbon nitride (CN) framework by a simple heated copolymerization method to construct a donor-acceptor (D-A) structure. Subsequently, the phenanthroline unit is coordinated with transition metal Fe3+ ions to obtain the photocatalyst Fe(III)-0.5-AP-CN with better nitrogen fixation performance, and the average NH3 yield can reach 825.3 µmol g-1 h-1. Comprehensive experimental results and theoretical calculations show that the presence of the D-A structure can induce intramolecular charge transfer, effectively separating photogenerated electrons and holes. The Fe active sites can improve the chemisorption energy for N2, enhance the N-Fe bonding, and better activate the N2 molecule. Therefore, the synergistic effect between the construction of the D-A structure and the stably dispersed Fe active sites can enable CN to achieve high-performance N2 reduction to produce NH3.

4.
Chem Asian J ; : e202400691, 2024 Sep 21.
Artigo em Inglês | MEDLINE | ID: mdl-39305145

RESUMO

For the first time acceptor-π-donor-π-acceptor (A-π-D-π-A) based Y-type organic electrode material have been designed and successfully utilized in supercapacitor (SC) application. This Y-type molecular architecture coined as AQ-Im-PTZ-Im-AQ based on anthraquinone (AQ) (A)-imidazole (Im) (π)- phenothiazine (PTZ) (D)- imidazole (Im) (π)-anthraquinone (AQ) (A) in combination with graphite foil (GF). As-fabricated PTZ-Im-AQ/GF and AQ-Im-PTZ-Im-AQ/GF electrode have shown the good energy storage properties in three-electrode supercapacitor system. Moreover, two-electrode symmetric supercapacitor (SSC) device based on AQ-Im-PTZ-Im-AQ/GF electrode exhibited specific capacitance (Csp) of 68.97 F g-1 at 1 A g-1 current density. The specific electron density (ED) of SSC was observed to be 12.06 Wh kg-1 at a specific power density (PD) of 1798.50 W kg-1. The SSC device exhibited 81.62% of Csp retention after 5000 galvanostatic charge-discharge (GCD) cycles.  For real world applications, AQ-Im-PTZ-Im-AQ/GF electrode was tested in symmetric Csp coin cell with applied potential voltage window of -0.4 to 1.0 V was found to be 112.32 F g-1 at 0.5 A g-1. Moreover, it realized high specific capacitance and high energy density of 19.66 Wh kg-1 at 891.94 W kg-1 power density. As a results, AQ-Im-PTZ-Im-AQ/GF make as an attractive electrode material for application in next-generation SCs.

5.
Angew Chem Int Ed Engl ; : e202416288, 2024 Sep 18.
Artigo em Inglês | MEDLINE | ID: mdl-39291657

RESUMO

We present a series of newly developed donor-acceptor (D-A) polymers designed specifically for organic electrochemical transistors (OECTs) synthesized by a straightforward route. All polymers exhibited accumulation mode behavior in OECT devices, and tuning of the donor comonomer resulted in a three-order-of-magnitude increase in transconductance. The best polymer gFBT-g2T, exhibited normalized peak transconductance (gm,norm) of 298±10.4 S cm-1 with a corresponding product of charge-carrier mobility and volumetric capacitance, µC*, of 847 F V-1 cm-1 s-1 and a µ of 5.76 cm2 V-1 s-1, amongst the highest reported to date. Furthermore, gFBT-g2T exhibited exceptional temperature stability, maintaining the outstanding electrochemical performance even after undergoing a standard (autoclave) high pressure steam sterilization procedure. Steam treatment was also found to promote film porosity, with the formation of circular 200 - 400 nm voids. These results demonstrate the potential of gFBT-g2T in p-type accumulation mode OECTs, and pave the way for the use in implantable bioelectronics for medical applications.

6.
Nanomicro Lett ; 17(1): 21, 2024 Sep 26.
Artigo em Inglês | MEDLINE | ID: mdl-39325321

RESUMO

Regulation the electronic density of solid-state electrolyte by donor-acceptor (D-A) system can achieve highly-selective Li+ transportation and conduction in solid-state Li metal batteries. This study reports a high-performance solid-state electrolyte thorough D-A-linked covalent organic frameworks (COFs) based on intramolecular charge transfer interactions. Unlike other reported COF-based solid-state electrolyte, the developed concept with D-A-linked COFs not only achieves electronic modulation to promote highly-selective Li+ migration and inhibit Li dendrite, but also offers a crucial opportunity to understand the role of electronic density in solid-state Li metal batteries. The introduced strong electronegativity F-based ligand in COF electrolyte results in highly-selective Li+ (transference number 0.83), high ionic conductivity (6.7 × 10-4 S cm-1), excellent cyclic ability (1000 h) in Li metal symmetric cell and high-capacity retention in Li/LiFePO4 cell (90.8% for 300 cycles at 5C) than substituted C- and N-based ligands. This is ascribed to outstanding D-A interaction between donor porphyrin and acceptor F atoms, which effectively expedites electron transferring from porphyrin to F-based ligand and enhances Li+ kinetics. Consequently, we anticipate that this work creates insight into the strategy for accelerating Li+ conduction in high-performance solid-state Li metal batteries through D-A system.

7.
J Environ Manage ; 370: 122599, 2024 Sep 27.
Artigo em Inglês | MEDLINE | ID: mdl-39340884

RESUMO

Diethyl phthalate (DEP) is a typical environmentally organic pollutant, widely used in the production process of polyvinyl chloride (PVC) to improve the flexibility of plastic materials. Its interaction with living organisms can inflict considerable harm to reproductive system functions. This research aims to utilize tetrahydrofuran (THF) to selectively break the chemical bonds in PVC molecules to provide more adsorption sites. Then incorporates the plasticizing assembly process of PVC to instantly remove and recover DEP from wastewater, achieving waste utilization, and sustainable environmental development. The research found that PTFR with a concentration of around 75 mg/L shows the best DEP removal efficiency. Sequencing batch processing removes more DEP compared to direct processing under the same material usage conditions. Furthermore, the recovery rate of DEP can reach over 90%. The technology demonstrates notable enhancements in removal efficiency and adsorption duration when compared to conventional adsorption techniques. This research has established an instant and efficient method for DEP removal, providing a new idea and technology for plasticizer treatment in practical wastewater.

8.
Chemistry ; : e202402984, 2024 Sep 29.
Artigo em Inglês | MEDLINE | ID: mdl-39343744

RESUMO

The hydroxamic acid functionality is present in various medicinal agents and has attracted special interest for synthetic transformations in both organic and medicinal chemistry. The N-O bond cleavage of hydroxamic acid derivatives provides an interesting transformation for the generation of various products. We demonstrate, herein, that O-benzyl-type protected hydroxamic acids may undergo photochemical N-O bond cleavage, in the presence or absence of a catalyst, leading to amides. Although some O-benzyl protected aromatic hydroxamates may be photochemically converted to amides in the presence of a base and anthracene as the catalyst, employing O-2-nitrobenzyl group allowed the smooth conversion of both aliphatic and aromatic hydroxamates to primary or secondary amides in good to excellent yields in the presence of an amine, bypassing the need of a catalyst. DFT and UV-Vis studies supported the effective generation of an electron donor-acceptor (EDA) complex between O-2-nitrobenzyl hydroxamates and amines, which enabled the successful product formation under these photochemical conditions. An extensive substrate scope was demonstrated, showcasing that both aliphatic or aromatic hydroxamates are compatible with this protocol, affording a wide variety of primary and secondary amides.

9.
Adv Healthc Mater ; : e2402545, 2024 Sep 16.
Artigo em Inglês | MEDLINE | ID: mdl-39279592

RESUMO

Developing stable and efficient photothermal agents (PTAs) for the second near-infrared window (NIR-II, 1 000-1700 nm) photothermal therapy (PTT) is highly desirable but remains challenging. Herein, a facile strategy to prepare NIR-II nano-PTA based on the ionic N-doped nanographene hexapyrrolohexaazacoronene (HPHAC) is reported featuring a specific orbicular-donor-acceptor (O-D-A) structure. Oxidizing HPHAC 1 to dication 12+ causes a substantial decrease in its band gap, leading to a shift in absorption from the confined UV region to a broad absorption range that reaches up to 1400 nm. The dication 12+ exhibits global aromaticity and excellent stability. Theoretical investigation demonstrates that the strong NIR-II absorption of 12+ is attributed to a distinct inner-to-outer intramolecular charge transfer. Encapsulating 12+ with amphiphilic polymers results in water-soluble 12+ NPs with retained optical characteristics. The 12+ NPs exhibit exceptional biocompatibility, intense photoacoustic responses, and a high photothermal conversion efficiency of 72% under the 1064 nm laser irradiation, enabling efficient PTT of cancer cells. The "O-D-A" system on HPHAC, which is created by a simple redox approach, provides a novel strategy to construct efficient NIR-II photothermal materials through molecular engineering of nanographenes.

10.
Small ; : e2405887, 2024 Sep 09.
Artigo em Inglês | MEDLINE | ID: mdl-39248647

RESUMO

Covalent organic frameworks (COFs) have emerged as one of the most studied photocatalysts owing to their adjustable structure and bandgaps. However, there is limited research on regulating the light-harvesting capabilities of acceptor building blocks in donor-acceptor (D-A) isomer COFs with different bond orientations. This investigation is crucial for elucidating the structure-property-performance relationship of COF photocatalysts. Herein, a series of D-A isostructural COFs are synthesized with different imine bond orientations using benzothiadiazole and its derivatives-based organic building units. Extended light absorption is achieved in COFs with acceptor groups that have strong electron-withdrawing capacities, although this resulted a decreased hydrogen generation efficiency. Photocatalytic experiments indicated that dialdehyde benzothiadiazole-based COFs, HIAM-0015, exhibit the highest hydrogen generation rate (17.99 mmol g-1 h-1), which is 15 times higher than its isomer. The excellent photocatalytic performance of HIAM-0015 can be attributed to its fast charge separation and migration. This work provides insights into the rational design and synthesis of D-A COFs to achieve efficient photocatalytic activity.

11.
Chem Asian J ; : e202400721, 2024 Aug 13.
Artigo em Inglês | MEDLINE | ID: mdl-39136408

RESUMO

Donor-acceptor (D-A) materials based on butterfly-shaped molecules could inhibit exciton-migration-induced quenching due to molecular twist. To explore this attribute towards beneficial photophysical properties, three novel bipolar acceptor-donor-acceptor (A-D-A) molecules with triphenyl triazine end capping along with substitution ortho to the Tröger's base (TB) scaffold varying from H, Me, and F were explored. The installation of H/Me/F imparted an electron push-pull effect with concomitant maneuvering of photophysical properties. On increasing solvent polarity, a remarkable bathochromic shift with a significant decrease in emission efficiency was observed due to the twisted intramolecular charge transfer state (TICT). Emission enhancement in the ethylene glycol-water mixture and diminution in the THF-water mixture further confirmed the existence of TICT states in these TBs. The torsional dynamics in the excited state were also evidenced by the time-dependent density-functional theory (TD-DFT) calculations. Owing to the butterfly architecture of the TB that suppressed TICT, TB-Trzs exhibited a significant blue shift, accompanied by a favorable quantum yield in the solid state. Among the three compounds, Me-TB-Trz exhibited deep-blue photoluminescence and was explored as a dopant in organic light-emitting diodes (OLEDs) to obtain deep-blue electroluminescence of brightness 4128 cdm-2 and CIE coordinates of (0.16, 0.09).

12.
Angew Chem Int Ed Engl ; : e202409926, 2024 Aug 18.
Artigo em Inglês | MEDLINE | ID: mdl-39155269

RESUMO

Imine-linked covalent organic frameworks (COFs) are garnering substantial interest in resistive random-access memory, attributed to their superior crystallinity, excellent chemical and thermal stability, and modifiable molecular structures. However, the development of high-performance COF-based memristors impeded by challenges such as low conjugation degree of imine bonds and poor electron delocalization ability. Herein, we report a protonation strategy to modify the imine bonds of donor-acceptor (D-A) type COFs. This modification significantly enhances the electron delocalization capability of imine bonds, lowers the energy barriers for electron injection from electrodes, and stabilizes the conductive charge transfer state, thus markedly improving device performance. The protonated COF-BTT-BPy and COF-BTT-TAPT thin films-based memristors show remarkable device performance with a high ON/OFF current ratio of 105, a low driving voltage, and outstanding endurance exceeding 600 and 1300 cycles, respectively, which is nearly twice the durability of analogous non-protonated COFs-based memristors. Notably, the protonated COF-BTT-TAPT-based memristor exhibit the highest number of cycles reported at present. This work not only unprecedentedly enhances the performance of COF-based memristors, but also provides a universal and promising approach for the molecular design and potential application of D-A type imine-linked COFs.

13.
Adv Mater ; 36(39): e2407199, 2024 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-39096075

RESUMO

Compared with conventional therapies, photoimmunotherapy offers precise targeted cancer treatment with minimal damage to healthy tissues and reduced side effects, but its efficacy may be limited by shallow light penetration and the potential for tumor resistance. Here, an acceptor-donor-acceptor (A-D-A)-structured nanoaggregate is developed with dual phototherapy, including photodynamic therapy (PDT) and photothermal therapy (PTT), triggered by single near-infrared (NIR) light. Benefiting from strong intramolecular charge transfer (ICT), the A-D-A-structured nanoaggregates exhibit broad absorption extending to the NIR region and effectively suppressed fluorescence, which enables deep penetration and efficient photothermal conversion (η = 67.94%). A suitable HOMO-LUMO distribution facilitates sufficient intersystem crossing (ISC) to convert ground-state oxygen (3O2) to singlet oxygen (1O2) and superoxide anions (·O2 -), and catalyze hydroxyl radical (·OH) generation. The enhanced ICT and ISC effects endow the A-D-A structured nanoaggregates with efficient PTT and PDT for cervical cancer, inducing efficient immunogenic cell death. In combination with clinical aluminum adjuvant gel, a novel photoimmunotherapy strategy for cervical cancer is developed and demonstrated to significantly inhibit primary and metastatic tumors in orthotopic and intraperitoneal metastasis cervical cancer animal models. The noninvasive therapy strategy offers new insights for clinical early-stage and advanced cervical cancer treatment.


Assuntos
Imunoterapia , Raios Infravermelhos , Neoplasias do Colo do Útero , Neoplasias do Colo do Útero/terapia , Neoplasias do Colo do Útero/patologia , Feminino , Animais , Imunoterapia/métodos , Humanos , Camundongos , Fotoquimioterapia/métodos , Linhagem Celular Tumoral , Fototerapia/métodos , Fármacos Fotossensibilizantes/química , Fármacos Fotossensibilizantes/farmacologia , Fármacos Fotossensibilizantes/uso terapêutico , Terapia Fototérmica/métodos , Nanopartículas/química
14.
Molecules ; 29(15)2024 Jul 28.
Artigo em Inglês | MEDLINE | ID: mdl-39124957

RESUMO

Group 14 metalloles have attracted much attention as core structures of conjugated functional materials. In this work, we prepared dithieno[3,2-b:4,5-c']germole as a new unsymmetrically condensed dithienogermole and benzo[4,5]thieno[2,3-c]germole as the benzene-condensed analog. The electronic states and properties of these unsymmetrically condensed germoles are discussed on the basis of the results of optical and electrochemical measurements with the help of quantum chemistry calculations on the simplified model compounds. The Stille cross-coupling reactions of bromodithieno[3,2-b:4,5-c']germole with di(stannylthienyl)- and di(stannylthiazolyl)benzothiadiazole provided conjugated donor-acceptor compounds that exhibited clear solvatochromic behavior in the photoluminescence spectra, indicating the potential application of the dithieno[3,2-b:4,5-c']germole unit as an electron donor in donor-acceptor systems.

15.
Small ; : e2405907, 2024 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-39148194

RESUMO

Photocatalytic H2O2 production is a green and sustainable route, but far from meeting the increasing demands of industrialization due to the rapid recombination of the photogenerated charge carriers and the sluggish reaction kinetics. Effective strategies for precisely regulating the photogenerated carrier behavior and catalytic activity to construct high-performance photocatalysts are urgently needed. Herein, a nitrogen-site engineering strategy, implying elaborately tuning the species and densities of nitrogen atoms, is applied for H2O2 photogeneration performance regulation. Different nitrogen heterocycles, such as pyridine, pyrimidine, and triazine units, are polymerized with trithiophene units, and five covalent organic frameworks (COFs) with distinct nitrogen species and densities on the skeletons are obtained. Fascinatingly, they photocatalyzed H2O2 production via dominated two-electron O2 reduction processes, including O2-O2 •‒-H2O2 and O2-O2 •‒-O2 1-H2O2 dual pathways. Just in the air and pure water, the multicomponent TTA-TF-COF with the maximum nitrogen densities triazine nitrogen densities exhibited the highest H2O2 production rate of 3343 µmol g-1 h-1, higher than most of other reported COFs. The theoretical calculation revealed the higher activity is due to the easy formation of O2 •‒ and O2 1 in different catalytic process. This study gives a new insight into designing photocatalysis at atomic level.

16.
Angew Chem Int Ed Engl ; : e202409421, 2024 Aug 13.
Artigo em Inglês | MEDLINE | ID: mdl-39136328

RESUMO

Realizing high-rate and high-capacity features of Lihium-organic batteries is essential for their practical use but remains a big challenge, which is due to the instrinsic poor conductivity, limited redox kinetics and low utility of organic electrode mateials. This work presents a well-designed donor-acceptor Covalent Organic Framework (COFs) with extended conjugation, mesoscale porosity, and dual redox-active centers to promote fast charge transfer and multi-electron processes. As anticipated, the prepared cathode with benzo [1,2-b:3,4-b':5,6-b''] trithiophene (BTT) as p-type and pyrene-4,5,9,10-tetraone (PTO) as n-type material (BTT-PTO-COF) delivers impressive specific capacity (218 mAh g-1 and 275 mAh g-1 at 0.2 A g-1 in ether-based and carbonate-based electrolyte respectively) and outstanding rate capability (79 mAh g-1 at 50 A g-1 in ether-based electrolyte and 124 mAh g-1 at 10 A g-1 in carbonate-based electrolyte). Moreover, the potential of BTT-PTO-COF electrode for prototype batteries has been demonstrated by full cells of dual-ion batteries, which attain comparable electrochemical performances to the half cells. Moreover, mechanism studies combining ex-situ characterization and theoratical calculations reveal the efficient dual-ion storage process and facile charge transfer of BTT-PTO-COF. This work not only expands the diversity of redox-active COFs but also provide concept of structure design for high-rate and high-capacity organic electrodes.

17.
Adv Sci (Weinh) ; : e2403454, 2024 Aug 26.
Artigo em Inglês | MEDLINE | ID: mdl-39188112

RESUMO

The donor-acceptor (D-A) dye 4-(bis-4-(5-(2,2-dicyano-vinyl)-thiophene-2-yl)-phenyl-amino)-benzoic acid (P1) has been frequently used to functionalize NiO photocathodes and induce photoelectrochemical reduction of protons when coupled to a suitable catalyst. Photoinduced twisting of the P1 dye is steered on NiO by co-adsorption of tetradecanoic acid (C14, myristic acid (MA)). Density Functional Theory and time-resolved photoluminescence studies confirm that twisting lowers the energy levels of the photoexcited D-A dye. The apolar environment provided by the MA suppresses photoinduced D-A twisting, retards charge recombination following photoinduced charge separation between P1 and NiO, and provides a larger electrochemical potential increasing the photocurrent. Very interestingly, co-adsorption of MA induces H2 evolution upon photoexcitation without the presence of an H2 evolution catalyst. Based on prior art, the formation of H2 is assigned to the dissolution of Ni2+, followed by reduction and re-deposition of Ni nanoparticles acting as the catalytically active site. It propose that only excited P1 with suppressed twisting provides the sufficient electrochemical potential to induce deposition of Ni nanoparticles. The work illustrates the importance of understanding the effects of photoinduced intramolecular twisting and highlights the promise of designing twisting-limited D-A dyes to create efficient solar fuel devices.

18.
Adv Sci (Weinh) ; : e2407117, 2024 Aug 29.
Artigo em Inglês | MEDLINE | ID: mdl-39206683

RESUMO

Replicating the microstructural basis and the near 100% excitation energy transfer efficiency in naturally occurring light-harvesting complexes (LHCs) remains challenging in synthetic energy-harvesting devices. Biological photosynthesis regulates active ensembles of light-absorbing and funneling chlorophylls in proteins in response to fluctuating sunlight. Here, use of long-range liquid crystal (LC) ordering to tailor chain orientation and packing structure in liquid crystalline conjugated polymer (LCCP) layers for bio-mimicry of certain structural basis and light-harvesting properties of LHCs is reported. It is found that long-range orientational ordering in an LC phase of poly(9,9-dioctylfluorene-co-benzothiadiazole) (F8BT) copolymer stabilizes a small fraction of randomly-oriented F8BT nanocrystals dispersed in an amorphous matrix of F8BT chains, resembling a self-doped host-guest system whereby excitation energy funneling and photoluminescence quantum efficiencies are enhanced significantly by triggering 3D donor-to-acceptor Förster resonance energy transfer (FRET) and dominant intrachain emission in the nano-crystal acceptor. Further, photoalignment of nematic F8BT layers is combined with LC orientational ordering to fabricate large-area-extended monodomains exhibiting >60% crystallinity and ≈20 nm-long interchain packing order. Remarkably, these monodomains demonstrate strong linearly polarized emission, whilst also promoting a new band-edge absorption species and an extra emissive interchain excited state as compared to the non-aligned films.

19.
Angew Chem Int Ed Engl ; : e202411180, 2024 Aug 27.
Artigo em Inglês | MEDLINE | ID: mdl-39192703

RESUMO

This work reports synthesis of a germylene based donor-acceptor molecule and its thermal excitation to a triplet state by coordination with a Lewis acid. Products have been characterized by single crystal X-ray diffraction, EPR spectroscopy, and SQUID measurement, in conjunction with DFT calculation. The singlet-triplet energy gap of the donor-acceptor molecule is dramatically reduced from -18.8 to -7.2 kcal/mol by the coordination with B(C6F5)3 (BCF), which enables an intramolecular single electron transfer from one germylene moiety to another upon heating, forming an intramolecular radical ion pair with diradical character. The work provides an approach to the formation of thermally populated open-shell species of heavier main group elements.

20.
Angew Chem Int Ed Engl ; : e202407166, 2024 Aug 13.
Artigo em Inglês | MEDLINE | ID: mdl-39138128

RESUMO

Covalent organic frameworks (COFs) offer remarkable versatility, combining ordered structures, high porosity, and tailorable functionalities in nanoscale reaction spaces. Herein, we report the synthesis of a series of isostructural, photoactive Wurster-type COFs achieved by manipulating the chemical and electronic nature of the Wurster aromatic amine building blocks. A series of donor-acceptor-donor (D-A-D) Wurster building block molecules was synthesized by incorporating heteroaromatic acceptors with varying strengths between triphenylamine donor groups. These tailored building blocks were integrated into a 2D COF scaffold, resulting in highly crystalline structures and similar morphologies across all COFs. Remarkably, this structural uniformity was also achieved in the synthesis of homogeneous and oriented thin films. Steady-state photoluminescence revealed a tunable red-shift in film emission exceeding 100 nm, demonstrating effective manipulation of their optical properties. Furthermore, photoelectrochemical studies exhibited a doubled current density (8.1 µA cm-2 at 0.2 VRHE) for the COF with the strongest acceptor unit. These findings highlight the potential of these D-A-D COFs in photoelectrochemical water splitting devices and pave the way for further exploration of structure-property relationships in this promising class of photoactive materials.

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