Intramolecular Donor-acceptor Research Articles

Frequency-Dependent Vibronic Effects in Steady State Energy Transport.

The interplay between electronic and intramolecular high-frequency vibrational degrees of freedom is ubiquitous in natural light-harvesting systems. Recent studies have indicated that an intramolecular vibrational donor-acceptor frequency difference can enhance energy transport. Here, we analyze the extent to which different intramolecular donor-acceptor vibrational frequencies affect excitation energy transport in the natural nonequilibrium steady state configuration. Comments are included on the less physical equilibrium case for comparison with the literature. It is found that for constant Huang-Rhys factors, whereas the acceptor population increases in the equilibrium case when the intramolecular vibrational frequency of the acceptor exceeds that of the donor, this increase is negligible for the nonequilibrium steady state. Therefore, these changes in acceptor population do not significantly enhance energy transport in the nonequilibrium steady state for the natural scenario of incoherent light excitation with biologically relevant parameters of typical photosynthetic complexes. Insight about a potential mechanism to optimize energy transfer in the nonequilibrium steady state based on increasing the harvesting time at the reaction center is analyzed.

A Strained Donor-Acceptor Carbon Nanohoop: Synthesis, Photophysical and Charge Transport Properties.

Herein, we report the synthesis of a novel intramolecular donor-acceptor (D-A) system ([12]CPP-8TPAOMe) based on cycloparaphenylenes (CPPs) grafted with eight di(4-methoxyphenyl)amino groups (TPAOMe) as donors. Compared to [12]CPP, D-A nanohoop exhibited significant changes in physical properties, including a large redshift (>78 nm) in the fluorescence spectrum and novel positive solvatofluorochromic properties with a maximum peak ranging from 484 nm to 546 nm. The potential applications of [12]CPP-8TPAOMe in electron- and hole-transport devices were further investigated, and its bipolar behavior as a charge transport active layer was clearly observed.

Rational design of g-C3N4-based photocatalysts with intramolecular donor-acceptor structures for deep oxidation of emerging organic micropollutants

An in-situ route for the fabrication of intramolecular electron donor-acceptor (D-A) structured g-C3N4 photocatalysts is developed by the preorganization of urea with the precursor of electron donor units, such as 4-iodobenzaldehyde, 5-bromo-2-thiophenaldehyde and 5-bromo-2-furaldehyde, followed by thermal polymerization. In the resulting benzene unit-, thiophene unit- and furan unit-based D-A structured g-C3N4 photocatalysts, namely, BHCNx, SCNx, and OCNx, the incorporated electron donor units (i.e., benzene units, thiophene units and furan units) link with the electron acceptors (i.e., heptazine units) through CN and CN covalent bonds. In comparison of bulk g-C3N4, all D-A structured g-C3N4 display notably enhanced visible-light photocatalytic oxidation activity in the degradation of emerging organic micropollutants, p-nitrophenol (PNP) and methylparaben (MPB), in which the apparent first-order kinetic constant of the optimized BHCN2, SCN2, and OCN2 is 1.6, 3.0 and 6.8 times higher than bulk g-C3N4 for PNP degradation and 1.9, 3.4 and 2.6 times higher than bulk g-C3N4 for MPB degradation. Importantly, the micropollutants can be not only degraded but also mineralized completely. The catalysts are also robust in the removal of mixed emerging organic micropollutants in pharmaceutical wastewater, exhibiting potential of dealing with organic micropollutants in wastewater. Mechanism studies reveal that the unique intramolecular charge transfer process in the catalysts enhances visible-light harvesting capacity, boosts directional transfer of the photogenerated charges and increases adsorption towards oxygen molecules. These collective improvements can maximum utilization the photogenerated electrons and holes to yield plentiful reactive oxygen species for deep oxidization of the pollutants.

Esterification and Etherification of Aliphatic Alcohols Enabled by Catalytic Strain-Release of Donor-Acceptor Cyclopropane.

We herein disclose a highly efficient protocol for the esterification and etherification of alcohols, leveraging a Sc(OTf)3-catalyzed ring-strain release event in the meticulously designed, chromatographically stable mixed anhydrides or benzyl esters that incorporate an intramolecular donor-acceptor cyclopropane (DAC). This versatile method facilitates the straightforward functionalization of sugar, terpene, and steroid alcohols under mild acidic conditions, as showcased by the single-catalyst-driven, dual protection of sugar diol.

BORON-NITROGEN COMPOUNDS IN THE REACTION OF BORIC AND BORONIC ACIDS WITH AMINES

The article is a review of boric or arylboronic acids reactions with aliphatic and aromatic amines. The review is for informational purposes only on the interaction of the acids in question with amines. It is shown that the data on the boric acid reaction with amines are contradictory and, at present, there is no confirmed information on obtaining a covalent bond between boron and nitrogen without the involvement of hydroxyl groups and the cyclic systems formation, for example, in the oxazaborolidines case. Literary searches have shown that the report on the anilinboronic acid production in 1963 was not developed, and there is also no data on the synthesis of those compounds. Along with this, boric acid easily forms borate salts of various configurations with amines, that is confirmed by modern methods of analysis (IR- and NMR-spectroscopy, elemental analysis). It has also been shown that boric acid is capable of forming compounds with an intramolecular donor-acceptor bond between boron and nitrogen. The theoretical calculations results and experimental data on the arylboronic acids interaction, with various aromatic ring substituents, with pyrocatechines, o-phenylenediamines, 2-hydroxybenzenetiols and o-benzenedithiols are presented. It is noted that competitive formation of anhydride-like structures is observed in all these reactions. It is shown that the interaction with pyrocatechins is the most thermodynamically advantageous. In the arylboronic acids reaction with ortho-benzenedithiols, ortho-hydroxybenzenetiols in chloroform, the corresponding oxathiaboroles and dithiaboroles were not isolated. The latter were obtained by the boron trichloride reaction with the corresponding electron donors. It is reported that there is no information on the preparation of condensation products of phenylboronic acids with aniline and benzylamine. For citation: Strokova S.V., Lenskiy M.A. Boron-nitrogen compounds in the reaction of boric and boronic acids with amines. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2024. V. 67. N 6. P. 6-13. DOI: 10.6060/ivkkt.20246706.6988.

Synthesis of bis-(benzhydryloxy) substituted axially silicon(IV) phthalocyanine: investigation of photophysical, photochemical, and computational electronic properties

Synthesis of axially disubstituted silicon(IV) phthalocyanine bearing benzhydryloxy groups obtained by reaction of SiPcCl2 with diphenylmethanol is reported. Characterization of the compound was performed by 1H and 13C NMR, UV–Vis, mass spectrometry, and FT-IR spectroscopy. Photophysical and photochemical properties were investigated. Fluorescence spectra measurements were performed in DMSO as solvent. A preferred chemical method was used to determine the amount of singlet oxygen production. Optimizations were calculated for the single-molecule Si-Pc with the 6–311 G (d, p) basis set at the B3LYP and B3PW91 levels of density functional theory (DFT). The charge transfer (or) charge delocalization between intramolecular donor–acceptor groups was determined by NBO analysis. Furthermore, molecular electrostatic potential, Fukui functions, electrophilic and nucleophilic character maps were calculated. The electronic structure and energy parameters of the investigated compound were determined to be ΔE calc = 2.19 eV by DFT calculation and ΔE opt = 1.84 by experimental UV spectrum.

Extended Conjugation Strategy Enabling Red-Shifted and Efficient Emission of Orange-Red Thermally Activated Delayed Fluorescence Materials.

In account of the energy gap law, the development of efficient narrow-band gap thermally activated delayed fluorescence (TADF) materials remains a major challenge for the application of organic light-emitting diodes (OLEDs). The orange-red TADF materials are commonly designed with either large π-conjugated systems or strong intramolecular donor-acceptor (D-A) interactions for red-shift emission and small singlet-triplet energy gap (ΔEST). There are rare reports on the simultaneous incorporation of these two strategies on the same material systems. Herein, two orange-red emitters named 1P2D-BP and 2P2D-DQ have been designed by extending the conjugation degree of the center acceptor DQ and increasing the number distribution of the peripheral donor PXZ units, respectively. The emission peak of 1P2D-BP is red-shifted to 615 nm compared to 580 nm for 2P2D-DQ, revealing the pronounced effect of the conjugation extension on the emission band gap. In addition, the distorted molecular structure yields a small ΔEST of 0.02 eV, favoring the acquisition of a high exciton utilization through an efficient reverse intersystem crossing process. As a result, orange-red OLEDs with both 1P2D-BP and 2P2D-DQ have achieved an external quantum efficiency (EQE) of more than 17%. In addition, the efficient white OLED based on 1P2D-BP is realized through precise exciton assignment and energy transport modulation, showing an EQE of 23.6% and a color rendering index of 82. The present work provides an important reference for the design of high-efficiency narrow-band gap materials in the field of solid-state lighting.

Synthesis of furan-based intramolecular donor–acceptor type chiral–electroactive polymers having optical activity, laser diffraction, and structural color functions

ABSTRACT A series of intramolecular donor–acceptor type monomers was polymerized in cholesteric liquid crystal (Ch-LC) electrolyte solution as a chiral liquid crystal molecular template with helical structure. The polymers thus obtained showing fingerprint pattern with iridescence via imprinting of Ch-LC medium were characterized by infrared spectroscopy, cyclic voltammetry, ultraviolet–visible spectroscopy, circular dichroism, scanning electron microscopy, polarizing microscopy, and reflectance spectroscopy to evaluate optical characters and structural color. The polymer showed optically active–electrochromism. The intramolecular donor–accepter type polymer has intermolecular chiral aggregation in the manner of Ch-LC by molecular form imprinting.

Introduction of electron-deficient unit in resorcinol-formaldehyde resin to construct donor–acceptor conjugated polymer for enhancing photocatalytic H2O2 production

Intramolecular donor–acceptor conjugated polymer was constructed in resorcinol-formaldehyde resin by embedding benzothiadiazole, which can reduce the Gibbs free energy for two-electron oxygen reduction and improve photocatalytic H2O2 evolution.

A novel graphitic carbon nitride photocatalyst with ultramicro amounts of intramolecular donor-acceptor structures for excellent photocatalytic hydrogen production

In this study, facile supramolecular thermal polymerization was employed for an attempt to modify graphitic carbon nitride (g-C3N4) using ultramicro amounts of diphenylamino-4-benzaldehyde as the dopant, and melamine and cyanuric chloride as the raw materials. The reaction of aldehyde-amine achieved diphenylamino-4-benzaldehyde grafting onto the edge of the heptazine ring of g-C3N4, resulting in the formation of a novel g-C3N4 with intramolecular twisted donor–acceptor (D-A) structures known as CN-Dxmg. It was confirmed that addition of 2 mg (0.67 wt‰) of diphenylamine-4-benzaldehyde as the donor regulated the energy level distribution of CN-D2mg, and as-obtained intramolecular D-A structures can promote the photogenerated carrier separation and migration of CN-D2mg through a directional channel for electron transfer from diphenylamine-4-benzaldehyde to heptazine. The results indicate that CN-D2mg photocatalyst has a high hydrogen production rate of 14581.1 μmol·h−1·g−1 at 420 nm under visible light irradiation, which is 1.6 times higher than that of pristine g-C3N4. The study presents an effective approach for large-scale applications involving g-C3N4 photocatalyst in clean energy production.

Intramolecular Donor–Acceptor Design in Porous Organic Framework for Liquid Fuels Adsorption Desulfurization

AbstractA porous organic framework containing well‐defined donor–acceptor units, named donor–acceptor porous organic framework (D–A‐POF), is successfully synthesized. The localized electric field gradient at the pore surface induced by the intramolecular donor–acceptor (D–A) interactions endows D–A‐POF with excellent desulfurization capabilities. D–A‐POF exhibits high adsorption capacity of 3‐methylthiophene (12.26 mmol g−1, 392.32 mg S g−1) and 1‐benzothiophene (793.65 mg g−1, 189.25 mg S g−1) with impressive adsorption selectivity. Density functional theory calculations provide compelling evidence of the preferential selective adsorption of aromatic thiophene sulfides in D–A‐POF. In fixed‐bed breakthrough experiments, D–A‐POF demonstrates its ability to selectively capture thiophene sulfides from model gasoline, resulting in fuel with sulfide content below 10 ppb. The high stability and high desulfurization efficiency of D–A‐POF make it promising as a new porous adsorbent for ultra‐depth adsorption desulfurization.

Construction of intramolecular donor–acceptor type carbon nitride for photocatalytic hydrogen production

High-efficiency photocatalysts based on organic polymeric semiconductor are often limited by slow charge separation kinetics and sluggish redox reaction dynamics. Herein, the donor–acceptor conjugated polymeric carbon nitride (D/A-CN) was synthesized by grafting benzene ring and pyridine moiety into the backbone of CN through a flexible pyrolysis strategy. The D/A-CN shows a high photocatalytic H2 evolution rate of 4795 µmol·h−1·g−1, which is ≈6.08 times higher than that of pristine CN (787.5 µmol·h−1·g−1). Both experimental and theoretical results confirm that the robust internal electric field is established in the D/A-CN framework due to the enhanced molecular dipole, which apply a kinetic force to facilitate the separation and mobility of photogenerated carriers. Meanwhile, the deeper conduction band potential caused by the elevated orbital energy level of D/A-CN contributes to the enhanced reduction ability of photoinduced electron. Consequently, the faster carrier transfer kinetics and the stronger thermodynamic reduction driving force synergistically lead to efficient photocatalytic H2 production of D/A-CN. This work reinforces the comprehension of the structure-performance relationship of donor–acceptor structural photocatalysts and provides an insight for enhancing the photocatalytic activity of polymeric photocatalysts at the molecular level.

Intramolecular D-A structure achieved excellent electrochemiluminescence of g-C3N4 originated from doping thiophene ring

The low electrochemiluminescence (ECL) efficiency and poor ECL stability of graphitic carbon nitride (g-C3N4) under high excitation potential due to obvious electrode passivation seriously restrict its further wider application. Here, construction of intramolecular donor–acceptor (D-A) structure had proposed to well resolve above problems, which had been rarely reported. As a research model, thiophene ring (electron donor, D) with strong electron donating property was doped into the heptazine (electron acceptor, A) of 3D g-C3N4. An intramolecular D-A structure of 3D Thing-g-C3N4 was obtained, which had extended π-conjugated system and high-speed intramolecular electron transfer. As a result, 3D Thing-g-C3N4 with intramolecular D-A structure exhibiting excellent cathodic ECL performance with endogenous dissolved O2 as coreactant under lower potential. Based on the above ECL system, an ultrasensitive biosensor was assembled for microRNA-221 detection with multiple HCR based cascade amplification strategy. The target-like DNA obtained through the initial HCR process induced by target could trigger multiple HCR processes again to realize the effective amplification of the target. The constructed biosensor had excellent detection performance for microRNA-221 and the detection limit was calculated as 5.25 aM. In conclusion, construction of intramolecular D-A structure was a novel and effective way to improve the ECL performance of g-C3N4, and the newly proposed multiple HCR based cascade amplification strategy paved provided new opportunities for the detection of cancer marker in early cancer diagnosis.

Synthesis and Photophysical Properties of Carbazole-Functionalized Diazaphosphepines via Sequent P-N Chemistry.

Chemical structure tunability of organic π-conjugated molecules (OCMs) is highly appealing for fine-tuning the optoelectronic properties. Herein, we report a new series of carbazole-functionalized diazaphosphepines (DPP-CBZs) via one-pot phosphorus-nitrogen (P-N) chemistry. The one-pot synthesis harnessed the mild and selective P-N chemistry that successively installed carbazole moieties and seven-membered heterocycles at one P-center. Single-crystal structure studies revealed the tweezer-like structures for 1PO, 2PO, and 3PO that maintained the intramolecular donor-acceptor interactions between [d]-aryl moieties and carbazole. DPP-CBZs exhibited a more twisted central-diazaphosphepine ring compared with the reference molecules (1-3MO without carbazole group). DPP-CBZs with strong electron-accepting [d]-Ars generally showed lower photoluminescence quantum yields (PLQYs) than those of the reference molecules, which is probably due to the intramolecular charge transfer (ICT) from electron-donating carbazole to electron-withdrawing [d]-Ars. Upon the oxidation of the P-centers, PLQYs of DPP-CBZs increased. Furthermore, photophysical studies and theoretical studies suggested that the carbazole group had a strong impact on the structures of DPP-CBZs. As a proof of concept, we showed that grinding the mixture of 1PO as the electron-donating tweezer and benzene-1,2,4,5-tetracarbonitrile (BzCN) as the electron acceptor induced the formation of the CT complex.

In Situ Construction of an Intramolecular Donor–Acceptor Conjugated Copolymer via Terephthalic Acid Derived from Plastic Waste for Photocatalysis of Plastic to Hydrogen Peroxide

In Situ Construction of an Intramolecular Donor–Acceptor Conjugated Copolymer via Terephthalic Acid Derived from Plastic Waste for Photocatalysis of Plastic to Hydrogen Peroxide

Enhanced imaging of protein-specific palmitoylation with HCR-based cis-membrane multi-FRET

Palmitoylation plays an important role in modulating protein trafficking, stability, and activity. The major predicament in protein palmitoylation study is the lack of specific and sensitive tools to visualize protein-specific palmitoylation. Although FRET approach was explored by metabolically labeled palmitic acid and antibody recognized target protein. The trans-membrane strategy suffers from low FRET efficiency due to the donor and acceptor located at different sides of membrane. Herein, we proposed a cis-membrane multi–fluorescence resonance energy transfer (multi–FRET) for amplified visualization of specific palmitoylated proteins through metabolic labeling and targeted recognition. The azido-palmitic acid (azido-PA) was metabolically incorporated into cellular palmitoylated proteins, followed by reacting with dibenzylcylooctyne-modified Cy5 (DBCO-Cy5) through copper-free click chemistry. The protein probe was attached to targeted protein by specific peptide recognition, which initiates a hybridization chain reaction (HCR) amplification process. The cis-membrane labeling method enables effective intramolecular donor-acceptor distance and allow to increase FRET efficiency. Simultaneously, HCR amplification triggered multi–FRET phenomenon with significantly improved FRET efficiency. With the superiority, this strategy has achieved the enhanced FRET imaging of palmitoylated PD-L1 and visualizing the palmitoylation changes of on PD-L1 under drug treatment. Furthermore, the established method successfully amplified visualization of PD-L1 palmitoylation in vivo and mice tumor slice. We envision the approach would provide a useful platform to investigate the effects of palmitoylation on the protein structure and function.

Dicyanovinyl-capped thiazologermoles with moderate donor-acceptor interaction as visible photoluminescence turn-on sensors for primary amines

Dicyanovinyl-capped thiazologermoles (DTzG-DCV and GIDTz-DCV) were synthesized, and their optical and electrochemical properties were investigated. Both DTzG-DCV and GIDTz-DCV showed solvatochromism, exhibiting red shifts of the photoluminescence (PL) bands with increasing solvent polarity from toluene to DMF, likely due to intramolecular donor–acceptor interaction. Moreover, they served as selective PL sensors, with spectral changes in the presence of amines and fluoride and iodide ions, but not other halogen ions, in solution. DTzG-DCV and GIDTz-DCV underwent a quick and high-yield reaction with n-butylamine to give imine derivatives, accompanied by PL color changes. Similar color changes were observed even in the solid state with n-butylamine and n-hexylamine. In contrast, reactions with secondary and tertiary alkylamines caused no obvious changes in PL color. The color changes are visible to the naked eye under irradiation with a portable UV lamp at 365 nm, and thus DTzG-DCV and GIDTz-DCV can be used for the quick and selective sensing of primary amines.

Tuning Local Charge Distribution in Multicomponent Covalent Organic Frameworks for Dramatically Enhanced Photocatalytic Uranium Extraction.

Optimizing the electronic structure of covalent organic framework (COF) photocatalysts is essential for maximizing photocatalytic activity. Herein, we report an isoreticular family of multivariate COFs containing chromenoquinoline rings in the COF structure and electron-donating or withdrawing groups in the pores. Intramolecular donor-acceptor (D-A) interactions in the COFs allowed tuning of local charge distributions and charge carrier separation under visible light irradiation, resulting in enhanced photocatalytic performance. By optimizing the optoelectronic properties of the COFs, a photocatalytic uranium extraction efficiency of 8.02 mg/g/day was achieved using a nitro-functionalized multicomponent COF in natural seawater, exceeding the performance of all COFs reported to date. Results demonstrate an effective design strategy towards high-activity COF photocatalysts with intramolecular D-A structures not easily accessible using traditional synthetic approaches.

Recent Progress in Conjugated Polymers-Based Donor–Acceptor Semiconductor Materials for Photocatalytic Hydrogen Evolution from Water Splitting

Exploration of high-efficiency stabilization and abundant source-conjugated polymers semiconductor materials with suitable molecular orbital energy levels has always been a hot topic in the field of photocatalytic hydrogen evolution (PHE) from water splitting. In the recent years, constructing the intramolecular donor–acceptor (D–A)-conjugated architecture copolymers has been proved as one of the most excellent photocatalyst modification tactics for optimizing the PHE properties because of unique advantages, including easy regulate band-gap position, fast transfer charge carrier in the intramolecular architecture, superior sunlight absorption capacity and range, large interfacial areas, and so forth. Therefore, in this minireview, we summarize the latest research progress of D–A architecture semiconductor materials for PHE from water splitting. First, we briefly overview the fundamental description and principles for the construction D–A heterostructures in the photocatalytic system. After that, the application of D–A architecture photocatalyst for PHE reaction over different classes of organic semiconductors have been discussed in detail. At last, the present development prospects and future potential challenges of D–A architecture materials are proposed. We hope this minireview has some parameter values for the further developments of intermolecular special structured organic semiconductor material in the future PHE research.

Insights into adsorption and high photocatalytic oxidation of ciprofloxacin under visible light by intra-molecular Donor-Acceptor like p-n isotype heterojunction: Performance and mechanism

Antibiotics, e.g. ciprofloxacin (CIP) are frequently detected in natural waters and sewage, however, the conventional sewage treatment techniques presents a great challenge for efficient removal them due to the inhibition of bacterial proliferation. Herein, the intra-molecular Donor-Acceptor like p-n isotype heterojunction of phosphorus and boron co-doped hollow tubular g-C3N4 (xB-PCN) was synthesized for high-efficiency visible light photocatalytic degradation of CIP. The Mott-Schottky curves showed that the xB-PCN exhibited both p and n-type conductivities, which probably because the doped boron has electron acceptor effect and the NH/NH2 groups could act as electron donors. This unique property enables xB-PCN to have excellent charge generation, separation and transfer ability for the highly efficient photodegradation of CIP, reaching 87.56% of decomposition efficiency within 1 h with the apparent rate constant (0.01151 min−1) of 6.85 times that of PCN. Furthermore, the 3B-PCN maintained high degradation percentage in tap water (84.63%) and aquaculture wastewater (78.41%). The results of LC-MS and TOC showed that CIP was gradually mineralized and the degradation pathways were proposed. Based on the radical trapping experiments and ESR characterization, the reactive oxygen species involved in the degradation of CIP were checked. This work offers a promising approach for treating antibiotics polluted water based on a metal-free conjugated polymeric g-C3N4.