Intramolecular Donor-acceptor Systems Research Articles

A facile covalent strategy for ultrafast negative photoconductance hybrid graphene/porphyrin-based photodetector

As a powerful complement to positive photoconductance (PPC), negative photoconductance (NPC) holds great potential for photodetector. However, the slow response of NPC relative to PPC devices limits their integration. Here, we propose a facile covalent strategy for an ultrafast NPC hybrid 2D photodetector. Our transistor-based graphene/porphyrin model device with a rise time of 0.2 ms and decay time of 0.3 ms has the fastest response time in the so far reported NPC hybrid photodetectors, which is attributed to efficient photogenerated charge transport and transfer. Both the photosensitive porphyrin with an electron-rich and large rigid structure and the built-in graphene frame with high carrier mobility are prone to the photogenerated charge transport. Especially, the intramolecular donor-acceptor system formed by graphene and porphyrin through covalent bonding promotes photoinduced charge transfer. This covalent strategy can be applied to other nanosystems for high-performance NPC hybrid photodetector.

Red‐Light‐Driven CO2Photoreduction into CH4and CO Enabled by Narrow‐Gap Conjugated Microporous Polymers

Herein, selective CO2photoreduction into CH4and CO with red light using conjugated microporous polymers (CMPs) at room temperature is reported. By incorporating electron‐rich pyrene and electron‐deficient fluorenone derivatives in the polymer networks to constructing intramolecular donor–acceptor system, the resulting three polymers show very broad light absorption covered from 350 to 1000 nm, with narrow gaps of 1.61–1.74 eV. In the presence of triethanolamine and 1‐benzyl‐1,4‐dihydronicotinamide as the sacrificial agents, P3 exhibits the best visible‐light reduction activity, with CH4and CO evolution rates of 932.9 and 943.4 μmol h−1 g−1, respectively. Most significantly, under the irradiation of red light (>600 nm), high evolution rates of CH4and CO for P3 are achieved at 293.7 and 282.6 μmol h−1 g−1, as well as nearly 100% reaction selectivity. The better performance of P3 than P1 and P2 can be ascribed to the high absorption toward CO2and improved charge transfer under light irradiation. This work opens great opportunities for designing broadband‐responsive CMPs for solar‐driven photocatalytic conversion.

Fabricating intramolecular donor-acceptor system via covalent bonding of carbazole to carbon nitride for excellent photocatalytic performance towards CO2 conversion

Photocatalytic conversion of CO2 into hydrocarbon fuels is an ideal technology of mitigating greenhouse effect caused by excessive emission of CO2. However, the high recombination rate of electron-hole pairs and limited charge carriers transport speed constrained the catalytic performance of many semiconductor catalysts. In this contribution, a series of carbon nitride (g-CN) samples with intramolecular donor-acceptor (D-A) system were successfully prepared by introducing organic donor into their structures. Characterization results confirmed that carbazole was successful connected to the structure of g-CN via chemical bond. The formation of intramolecular D-A system greatly enlarged the light response region of g-CN-xDbc. In addition, a new charge transfer transition mode was formed in g-CN-0.01Dbc due to the incorporation carbazole, which enable it to use light with energy lower than the intrinsic absorption of g-CN. Meanwhile, the D-A structure led to the spatial separation of electrons and holes in g-CN-xDbc and significantly decreased the recombination rate of electron-hole pairs. The g-CN-0.01Dbc presented the best catalytic performance and the CO evolution rate was 9.6 times higher than that of g-CN. Moreover, the reaction was performed in water without any additive, which made it green and sustainable. DFT simulation confirmed the D-A structure and charge carrier migration direction in the prepared samples.

Fabricating C and O co-doped carbon nitride with intramolecular donor-acceptor systems for efficient photoreduction of CO2 to CO

Photocatalytic reduction of CO2 to hydrocarbon fuels is an ultimate and utmost strategy to resolve the ever-increasing environmental problems and energy crisis. Our study aimed to develop a specific type of photocatalysts with increasing light utilization efficiency, reducing electron-hole recombination rate and enhancing photocatalytic activity by integrating unique donor-acceptor systems into the polymeric network of graphitic carbon nitride (g-CN). The results of the characterization showed that C and O are successfully integrated into the framework of g-CN. The O-containing and C-containing section of the as-prepared catalysts (OCCNx) play the role of donor and acceptor, respectively. The donor-acceptor systems of OCCNx offer an extra electron transfer transition mode, which dramatically extends the optical absorption range, and narrows down the bandgap of g-CN from 2.74 to 2.03 eV. Also, the donor-acceptor systems significantly improve the delocalized ability of the photoinduced charge carriers, which efficiently prolongs the lifetime of the charge carriers and reduces the electron-hole recombination rate, as all of these are all beneficial for boosting the photocatalytic activity of the catalysts. Experimental results show that OCCN0.25 displays the best photocatalytic CO2 reduction performance with a CO production rate of 34.97 μmol g−1 in 4 h, which is 4.3-fold higher than that obtained in the case of bulk g-CN. Moreover, the reaction is performed in water without any co-catalyst and sacrificial agent, which makes it a green and environmentally friendly reaction. Results obtained from DFT simulation agree well with the empirical results, and a possible reaction mechanism is suggested based on these calculations.

Cationic, Methylene-Bridged, Intramolecular Donor-Acceptor Systems Based on Zirconium and Hafnium and Phosphino-methanides

A new access to cationic zirconium and hafnium compounds [L2MCH2PR2][MeB(C6F5)(3)] (L = Cp, Ind; R = iso-Pr, tert-Bu; M = Zr, Hf) exhibiting an intramolecular donor-acceptor system was established by treating the precursors L2M(Me)CH2PR2 with B(C6F5)(3) (BCF). Precursors 1-6 [L2M(Me)CH2PR2 with L = Cp, Ind; R = iso-Pr, tert-Bu; M = Zr, Hf] were fully characterized. The crystal structures of these compounds revealed large M-CH2-P bond angles with values of about 134 degrees indicating the absence of interactions between the Lewis-acid and Lewis-base. The cationic compounds [L2MCH2PR2][MeB(C6F5)(3)] (7-12) were obtained by treatment of 1-6 with BCF. They were characterized by NMR spectroscopy, mass spectrometry, and elemental analyses; in H/D-scrambling experiments with H-2/D-2 mixtures 7-12 disclosed their reactivity towards cleavage of hydrogen.

Methylene-bridged, intramolecular donor–acceptor systems based on rare-earth metals and phosphinomethanides

New geminally bonded intramolecular donor-acceptor systems, Cp2LnCH2PR2 (Ln = Y, Ho, Er, R = CHMe2, CMe3), were prepared by salt elimination reactions between the dicyclopentadienyl-element chlorides (Cp2LnCl, Ln = Y, Ho, Er) and diorganylphosphinomethanides (R2PCH2Li; R = CHMe2, CMe3). These compounds, 1-6, were characterized by elemental analyses, mass spectrometry and X-ray diffraction experiments and the yttrium species additionally by NMR spectroscopy. In the solid state the molecular structures differ from each other, depending on the steric demand of the phosphorus substituents. For all iso-Pr-substituted compounds, dimers [Cp2LnCH2P(CHMe2)2]2 with six-membered Ln-C-P-Ln-C-P rings in a chair-like conformation were observed. The sterically more demanding tert-butyl groups prevent dimerization but instead lead to species that undergo complexation of LiCl units by two monomers: [Cp2LnCH2P(CMe3)2·LiCl]. The solution NMR data for the yttrium compounds are consistent with the solid-state structures. Conversion with phenylacetylene afforded heteroleptic cyclobutane-like alkynyl-rare-earth metal complexes [Cp2Ln(μ-C[triple bond, length as m-dash]CPh)]2 [Ln = Y (7), Ho (8), Er (9)]. Treatment of compounds 1-6 with 1,8-diethynylanthracene led to single metalation and dimerization and products with similar structural motifs as observed for complexes 7-9. Reactions with dihydrogen and carbon dioxide resulted in Y-C bond breaking, yielding Cp2YH/R2PCH3 and CO2 insertion products, respectively.

Conjugated donor–acceptor copolymers derived from phenylenevinylene and trisubstituted pyridine units

Copolymers having intramolecular donor–acceptor systems encompassing trisubstituted pyridine derivatives as acceptor and phenylenevinylene (PPV) unit as a donor segment were synthesized. In addition, thiophene-containing random terpolymer PPVPYT via palladium-catalyzing Heck coupling reaction is reported. The novel-substituted pyridine monomers (PYBr) are synthesized by adopting a one-pot synthesis method using p-toluenesulfonic acid as catalyst in ethanol medium, which results in an excellent yield of about 95%. All the copolymers Poly phenylenevinylene-co-Pyridine derivatives (PPVPY) and terpolymers of Polyphenylenevinylene-co-Pyridine and Thiophene (PPVPYT) are found to be soluble in organic solvents, such as tetrahydrofuran, chloroform, and N, N-dimethylformamide. The molecular weights of the synthesized polymers were characterized by gel permeation chromatography (GPC), and their chemical structures were confirmed by infra red and nuclear magnetic resonance spectroscopies. The electrochemical band gaps of PPVPY-1, PPVPY-2, and PPVPY-3 copolymers are estimated to be 2.55, 2.48, and 2.0, respectively. Similarly, the band gap of PPVPY75T25, PPVPY50T50, and PPVPY25T75 random copolymers are estimated as 2.31, 1.95, and 2.23, respectively. These polymers also show excellent optical and thermal properties.

Spectra and dynamics of an ionic styryl dye in reverse micelles

The interesting influence on the photophysics of an intramolecular donor–acceptor system 2-(4-(dimethylamino) styryl)-1-methylpyridinium iodide (DASPMI), a known selectively staining agent of mitochondria in living cells, by the monodispersed biomimicking nanocavities formed by the anionic sodium 1,4-bis-2-ethylhexylsulfosuccinate (AOT)/n-heptane and the cationic benzyl-n-hexadecyl dimethylammonium chloride (BHDC)/benzene reverse micelles and also water-in-oil (n-heptane/(AOT)/water or benzene/(BHDC)/water) have been reported in this paper. Red shift of DASPMI emission in AOT with increasing water pool size ( W = [H 2O]/[surfactant]) indicates that the probe molecule moves towards core and the blue shift in BHDC in the same condition is indicative of the probe remaining away from the core. The partition constant K p in two RMs correlate well with the position of emitting probe DASPMI in RMs interface and it corresponds nicely with the values obtained from anisotropy data. Reduced quantum yield of TICT emission with increasing pool size ( W) in AOT due to non-radiative decay through hydrogen bonding suggests that the acceptor group is at the interface directed towards water pool. In AOT decreasing anisotropy along with active non-radiative channel confirm the presence of the probe at the water/AOT interface. The rotational restriction experienced by DASPMI in anionic reverse micelle decreases with increasing hydration. The in situ measurements of micropolarity and microviscosity around the probe with increasing W show enhanced micropolarity and a decrease in microviscosity. Increased emission quenching by Cu 2+ is due to counterion exchange of Cu 2+ by Na + at the micellar interface and due to increased local concentration of Cu 2+. It again confirms that the probe molecule does not penetrate into the core rather it binds at the interfacial region. The unaffected TICT emission in fluorescence quenching study in BHDC confirms position of probe away from the core.

Role of a phthalocyanine–fullerene dyad in multilayered organic solar cells

A double-bridged phthalocyanine–fullerene dyad (H 2Pc–C 60ee) was used as photo-active intramolecular donor–acceptor system in a layered organic solar cell. In this device, a poly(3-hexylthiophene) (PHT) film was used as electron donor, whereas either C 60 or perylene tetracarboxylic diimide (PTCDI) film was selected as electron acceptor. The introduction of the dyad layer leads to an enhancement of the power conversion efficiency ( η ) in all the examples, mainly due to an increase of the open-circuit voltage. By introducing the dyad in PTCDI-containing cells, the efficiency (being 0.32%) was enhanced by almost three times compared to that of the reference (0.12%). In C 60-containing cells, the efficiency of the dyad sample (being 0.30%) was over one and half times higher than that of the reference in the absence of the dyad (0.18%). The role of such a dyad in the solar cells is discussed in detail.

An experimental and computational study of intramolecular charge transfer: Diarylamino derivatives of 7 H-benzimidazo(2,1- a)benz( d, e)isoquinolin-7-ones

A novel intramolecular donor–acceptor system of four isomers consisting of 7 H-benzimidazo(2,1- a)benz( d, e)isoquinolin-7-ones and diarylamine units was synthesized and characterized; the absorption and fluorescence spectra of the system in a variety of solvents were investigated. Intramolecular charge transfer was confirmed within the system by virtue of shifts in emission maximum with increasing solvent polarity; a high dipole moment for the intramolecular excited state was calculated using the Lippert equation. Shorter lifetimes were observed in polar solvents compared with those in non-polar solvents, indicating strong dipole–dipole interactions occurred. The ground-state geometry, lowest energy transition and the UV–vis spectrum of the system were studied using density functional theory and time-dependent density functional theory at B3LYP/6-31G ∗ level, which showed that the calculated outcomes were in good agreement with experimental data.

Hydroquinone–Benzonitrile System: Intramolecular Charge-Transfer and Computational Studies

A novel intramolecular donor-acceptor system of hydroquinone-benzonitrile was synthesized. Its photo-induced intramolecular charge-transfer (ICT) transition was confirmed by (1) shift of its emission maximum with increasing solvent polarity, (2) high dipole moment for the ICT excited state calculated from the Lippert equation, and (3) its HOMO and LUMO. According to the extent of separation between HOMO and LUMO, it is suggested that substituent position (ortho, meta, or para) in the donor-acceptor biphenyls is not a key point for the photo-induced intramolecular charge transfer and the donor with two alkoxy or hydroxy groups has more photo-induced charge transfer transitions than the one with one alkoxy or hydroxy group. In other words, the hydroquinone-benzonitrile system displays more photo-induced charge transfer transitions than 4COB (4-cyano-4'-butyloxybiphenyl).

Mono- and biphotonic photochemistry in glass matrices

Photochemistry in hard glassy solvent matrices gives different results than in gas matrices. It is performed at 83, 77, and ≥10 K by continuous irradiation and by pulsed multi MW cm −2 peak intensity excitation for those systems that do not react monophotonically. The highly structured matrix spectra should be taken as a basis for the interpretation of transient spectra to avoid ambiguities. Numerous [2.2]paracyclophanes are photolyzed. Most of them give stable diradical and quinodimethane spectra in addition to fluorescence and phosphorescence. Some benzylic diradicals undergo chemiluminescence after their photochemical generation. Matrix isolation spectroscopy is at variance with common interpretations in the lepidopterene case. A [2+4]-photocycloreversion of a substituted cyclohexene at 83 K leads to diene stereoisomers/rotamers that isomerize upon further irradiation. E/Z-photoequilibria are obtained in MTHF matrix from both sides with ω-nitrostyrene and α-benzylidene-γ-butyrolactone at 83 K, the latter stereoisomerization was also successfully studied at 10 K. Pulsed irradiation of technical photostabilizers at 10 K leads to stable zwitterion formation by proton migration that cannot be seen by continuous excitation. Inter- and intramolecular donor acceptor systems provide stable charge separation at 15 or 77 K upon pulsed laser irradiation and radicalanion spectra are recorded. Biphotonic photochemistry at ≥10 K allows for the formation of new ring systems such as dioxathiirane ( cyclo-SO 2), several aryldioxaziridines, and an electron rich triaziridine, compounds that revert upon thawing and could not be obtained by continuous irradiation, except cyclo-SO 2 that can also be formed after absorption of the long lived SO 2 triplet by another two-photon process.

Photophysics and photovoltaic device properties of phthalocyanine–fullerene dyad:conjugated polymer mixtures

The phthalocyanine–fullerene dyad Pc-C60 is an intramolecular donor–acceptor system that can be used as photoactive material in photovoltaic devices. The photocurrent shows maxima below 400 and 700 nm, but only a small response in the range around 500 nm. To improve the spectral match to the solar emission spectrum, an energy transfer process from the conjugated polymer poly [2-methoxy-5-(3′,7′-dimethyloctyloxy)-1-4-phenylene vinylene] MDMO-PPV (antenna system) to the dyad compound can be used. The photophysics of the energy transfer process was studied with luminescence measurements and sub-picosecond time-resolved transmission changes. The influence of the polymeric antenna system on the photovoltaic device properties was measured with spectrally resolved photocurrent (IPCE) measurements. Photocurrent in nearly the full visible spectral range was obtained. In addition, Pc-C60 was also added as third component to MDMO-PPV:PCBM mixtures. The photocurrent around 700 nm was increased, however with reduction in the short-circuit current under white light illumination.

Intramolecular donor-acceptor systems. 7. Solvent dielectric relaxation effects on the photophysics of 6-(phenylamino)-N,N-dimethyl-2-naphthalenesulfonamides

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTIntramolecular donor-acceptor systems. 7. Solvent dielectric relaxation effects on the photophysics of 6-(phenylamino)-N,N-dimethyl-2-naphthalenesulfonamidesE. M. Kosower, H. Kanety, H. Dodiuk, G. Striker, T. Jovin, H. Boni, and D. HuppertCite this: J. Phys. Chem. 1983, 87, 14, 2479–2484Publication Date (Print):July 1, 1983Publication History Published online1 May 2002Published inissue 1 July 1983https://doi.org/10.1021/j100237a010RIGHTS & PERMISSIONSArticle Views98Altmetric-Citations32LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (607 KB) Get e-Alerts

Intramolecular donor-acceptor systems: Part 8. Solvent and substituent effects on the fluorescence emission of 6- N-methyl- N-phenylamino-2-naphthalenesulfon- N, N-dimethylamides

The dual fluorescence (emissions from S 1,np and S 1,ct states) of N-phenylaminonaph-thalenesulfonate (ANS) systems is briefly reviewed. The 6- N-methyl- N-phenylamino-2-naphthalenesulfon- N, N-dimethylamides also exhibit dual fluorescence, as shown by plots of emission energy and Φ F against the solvent polarity parameter, E T(30). The solvent polarities, for which appearance of S 1,ct emission marks the occurrence of an intramolecular electron transfer (i.e.t.) process, are appreciably lower than those of the corresponding sulfonates. The fluorescence of the dimethylamides exhibits a high sensitivity to substituent change, the apparent Hammett ϱ value being ca. −13 for unsubstituted dimethylamide and −33 for N-methyl-substituted dimethylamide. The N, N-dimethylamides are particularly suitable for the investigation of the rates and mechanisms of intramolecular electron-transfer processes by picosecond and nanosecond pulse techniques.

ChemInform Abstract: INTRAMOLECULAR DONOR‐ACCEPTOR SYSTEM. 4. SOLVENT EFFECTS ON RADIATIVE AND NONRADIATIVE PROCESSES FOR THE CHARGE‐TRANSFER STATES OF N‐ARYLAMINONAPHTHALENESULFONATES

Chemischer InformationsdienstVolume 9, Issue 39 Physical Organic Chemistry ChemInform Abstract: INTRAMOLECULAR DONOR-ACCEPTOR SYSTEM. 4. SOLVENT EFFECTS ON RADIATIVE AND NONRADIATIVE PROCESSES FOR THE CHARGE-TRANSFER STATES OF N-ARYLAMINONAPHTHALENESULFONATES E. M. KOSOWER, E. M. KOSOWERSearch for more papers by this authorH. DODIUK, H. DODIUKSearch for more papers by this authorH. KANETY, H. KANETYSearch for more papers by this author E. M. KOSOWER, E. M. KOSOWERSearch for more papers by this authorH. DODIUK, H. DODIUKSearch for more papers by this authorH. KANETY, H. KANETYSearch for more papers by this author First published: September 26, 1978 https://doi.org/10.1002/chin.197839047AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume9, Issue39September 26, 1978 RelatedInformation

Intramolecular donor-acceptor systems. 3. A third type of emitting singlet state for N-alkyl-6-N-arylamino-2-naphthalenesulfonates. Solvent modulation of substituent effects on charge-transfer emissions

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTIntramolecular donor-acceptor systems. 3. A third type of emitting singlet state for N-alkyl-6-N-arylamino-2-naphthalenesulfonates. Solvent modulation of substituent effects on charge-transfer emissionsEdward M. Kosower and Hanna DodiukCite this: J. Am. Chem. Soc. 1978, 100, 13, 4173–4179Publication Date (Print):June 1, 1978Publication History Published online1 May 2002Published inissue 1 June 1978https://doi.org/10.1021/ja00481a027RIGHTS & PERMISSIONSArticle Views144Altmetric-Citations55LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (771 KB) Get e-Alerts Get e-Alerts

Intramolecular donor-acceptor system. 4. Solvent effects on radiative and nonradiative processes for the charge-transfer states of N-arylaminonaphthalenesulfonates

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTIntramolecular donor-acceptor system. 4. Solvent effects on radiative and nonradiative processes for the charge-transfer states of N-arylaminonaphthalenesulfonatesEdward M. Kosower, Hanna Dodiuk, and Hanna KanetyCite this: J. Am. Chem. Soc. 1978, 100, 13, 4179–4188Publication Date (Print):June 1, 1978Publication History Published online1 May 2002Published inissue 1 June 1978https://doi.org/10.1021/ja00481a028RIGHTS & PERMISSIONSArticle Views396Altmetric-Citations88LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (969 KB) Get e-Alerts Get e-Alerts

Intramolecular donor-acceptor systems. Radiative and nonradiative processes for the excited states of 2-N-arylamino-6-naphthalenesulfonates

Intramolecular donor-acceptor systems. Radiative and nonradiative processes for the excited states of 2-N-arylamino-6-naphthalenesulfonates