New electroactive asymmetrical chalcones and therefrom derived 2-amino- / 2-(1H-pyrrol-1-yl)pyrimidines, containing an N-[ω-(4-methoxyphenoxy)alkyl]carbazole fragment: synthesis, optical and electrochemical properties

• Daria G. Selivanova,
• Alexei A. Gorbunov,
• Olga A. Mayorova,
• Alexander N. Vasyanin,
• Igor V. Lunegov,
• Elena V. Shklyaeva and
• Georgii G. Abashev

Beilstein J. Org. Chem. 2017, 13, 1583–1595, doi:10.3762/bjoc.13.158

• example, compounds 7a,b demonstrate a yellow fluorescence in dichloromethane, DMF, acetone, and an orange one in ethanol, that is most likely connected with the enhancement of the intramolecular charge transfer under UV irradiation. The prepared compounds differ from each other only by the nature of the

• shown that incorporation of a thiophene unit into the structure of compounds 5a,b enforces the intramolecular charge transfer, which, in its turn, causes the decrease in the difference between the energy of the ground and excited states and the appearance of additional absorption bands in the 350–400 nm

• * electron transition, that occurs most likely due to the presence of a chlorine atom with lone electron pairs. The above mentioned intramolecular charge transfer inherent to quadrupolar chromophores (D–A–D or A–D–A), also leads to the generation of the positive solvatochromism effects in these systems [26

Molecular-level architectural design using benzothiadiazole-based polymers for photovoltaic applications

• Vinila N. Viswanathan,
• Arun D. Rao,
• Upendra K. Pandey,
• Arul Varman Kesavan and
• Praveen C. Ramamurthy

Beilstein J. Org. Chem. 2017, 13, 863–873, doi:10.3762/bjoc.13.87

• studied by UV–vis spectroscopy. The absorption spectra were obtained in chlorobenzene solution (Figure 4). All polymers showed a broad absorption in the lower energy region (450–650 nm) due to the intramolecular charge transfer (ICT) through the backbone of polymers and another broad peak in the higher

Spectral and DFT studies of anion bound organic receptors: Time dependent studies and logic gate applications

• Srikala Pangannaya,
• Neethu Padinchare Purayil,
• Shweta Dabhi,
• Venu Mankad,
• Prafulla K. Jha,
• Satyam Shinde and
• Darshak R. Trivedi

Beilstein J. Org. Chem. 2017, 13, 222–238, doi:10.3762/bjoc.13.25

• the transitions between the π orbital of the azomethine group and the OH functionality involved in an intramolecular charge-transfer process, respectively [38]. The incremental addition of 0.1 equiv of TBA salts of F− and AcO− resulted in a red shift of the original charge-transfer bands to 477 nm and

• in the presence of F− and AcO− ions were also studied. A significant reduction of ΔE to 0.0679 Ha (R1 + F−), 0.04 (R1 + AcO−) and 0.08 Ha (R2 + F− and R2 + AcO−) confirms the presence of intramolecular charge-transfer transitions during the anion detection process. The similar values of ΔE observed

• from 0.96 Å to 1.47 Å and 1.55 Å reflects the host–guest interaction. Mulliken charge distribution calculations showed a change of the atomic charge on the oxygen atom of receptors R1 and R2 from less negative to more negative values which are indicative for an intramolecular charge transfer process

Effect of the π-conjugation length on the properties and photovoltaic performance of A–π–D–π–A type oligothiophenes with a 4,8-bis(thienyl)benzo[1,2-b:4,5-b′]dithiophene core

• Ni Yin,
• Lilei Wang,
• Yi Lin,
• Jinduo Yi,
• Lingpeng Yan,
• Junyan Dou,
• Hai-Bo Yang,
• Xin Zhao and
• Chang-Qi Ma

Beilstein J. Org. Chem. 2016, 12, 1788–1797, doi:10.3762/bjoc.12.169

• acceptor unit, on the other hand, will change the intramolecular charge transfer state and tune the light absorption ability, which will consequently change the photovoltaic performance of the materials as well. The third possible structure modification of BDT derivatives is to tune the conjugation length

Synthesis and characterization of benzodithiophene and benzotriazole-based polymers for photovoltaic applications

• Desta Gedefaw,
• Marta Tessarolo,
• Margherita Bolognesi,
• Mario Prosa,
• Renee Kroon,
• Wenliu Zhuang,
• Patrik Henriksson,
• Kim Bini,
• Ergang Wang,
• Michele Muccini,
• Mirko Seri and
• Mats R. Andersson

Beilstein J. Org. Chem. 2016, 12, 1629–1637, doi:10.3762/bjoc.12.160

• ascribed to intramolecular charge-transfer-like interactions between the monomers and interchain interactions [23][24], respectively. However, despite the similar molecular structures, the different absorption spectra of PTzBDT-1 and PTzBDT-2 confirm the crucial role of the aryl side groups on the

Star-shaped and linear π-conjugated oligomers consisting of a tetrathienoanthracene core and multiple diketopyrrolopyrrole arms for organic solar cells

• Hideaki Komiyama,
• Chihaya Adachi and
• Takuma Yasuda

Beilstein J. Org. Chem. 2016, 12, 1459–1466, doi:10.3762/bjoc.12.142

• acceptor–donor–acceptor electronic structures, an electron-donating TTA unit was coupled with electron-accepting diketopyrrolopyrrole (DPP)-based chromophoric units, which are well-known building blocks used in OSCs [28][29][30][31]. Such molecular structures facilitate intramolecular charge transfer

• nm) originating from intramolecular charge transfer (ICT) transitions between the electron-donating TTA and the electron-accepting DPP units. Evidently, the maximum absorption coefficient (ε) of TTA-DPP4 (22.3 × 104 M−1 cm−1) is more than twice that of TTA-DPP2 (9.6 × 104 M−1 cm−1), which is

Tetrathiafulvalene-based azine ligands for anion and metal cation coordination

• Awatef Ayadi,
• Aziz El Alamy,
• Olivier Alévêque,
• Magali Allain,
• Nabil Zouari,
• Mohammed Bouachrine and
• Abdelkrim El-Ghayoury

Beilstein J. Org. Chem. 2015, 11, 1379–1391, doi:10.3762/bjoc.11.149

• dinitrophenylhydrazone group). As compared to ligand L1, L2 exhibits an additional absorption band around λ = 516 nm which is attributed to an intramolecular charge transfer (ICT) excitation from the TTF donor moiety to the dinitrophenylhydrazone accepting group. These results from a strong π-electronic delocalization

• electron-accepting dinitrophenyl group as well as a coordinating pyridine azine moiety were successfully synthesized. Ligand L2 exhibit a strong electronic conjugation between the donor and the acceptor resulting in the occurrence of an intramolecular charge transfer (ICT) band between the two fragments

A hybrid electron donor comprising cyclopentadithiophene and dithiafulvenyl for dye-sensitized solar cells

• Gleb Sorohhov,
• Chenyi Yi,
• Michael Grätzel,
• Silvio Decurtins and
• Shi-Xia Liu

Beilstein J. Org. Chem. 2015, 11, 1052–1059, doi:10.3762/bjoc.11.118

• synthesized and characterized. Both of them undergo two reversible oxidations and strongly absorb in the visible spectral region due to a photo-induced intramolecular charge-transfer (ICT) transition. To a great extent, the electronic interaction between the D and A units is affected by the presence of a

• unit. Keywords: donor–acceptor systems; dye-sensitized solar cells; electrochemistry; intramolecular charge transfer; Knoevenagel reaction; tetrathiafulvalene; Introduction Dye-sensitized solar cells (DSSCs) have been intensively investigated as an alternative to silicon-based solar cells [1][2][3][4

• -donor (D) and an electron-acceptor (A) unit linked through a π-bridge, leading to a broad and intense optical absorption band in the visible spectral region due to an effective intramolecular charge transfer (ICT) from D to A units. To develop high-efficient DSSCs, a variety of organic donors [2][6][7

Fluoride-driven ‘turn on’ ESPT in the binding with a novel benzimidazole-based sensor

• Kai Liu,
• Xiaojun Zhao,
• Qingxiang Liu,
• Jianzhong Huo,
• Bolin Zhu and
• Shihua Diao

Beilstein J. Org. Chem. 2015, 11, 563–567, doi:10.3762/bjoc.11.61

• potential utility to detect fluoride. Based on the aforementioned UV–vis, spectrofluorimetric and 1H NMR studies, the possible mechanism of F− recognition by BIP was proposed and illustrated in Scheme 2. On binding of F−, the isomerization of BIP was restricted, which enhanced the intramolecular charge

• transfer interaction between the assembly of binding sites with F− to the chromophore [1]. With further addition of F−, intermolecular hydrogen bond formation disturbed the intramolecular hydrogen bonding and destroyed the geometrically restricted conformation [2], at the same time, the new geometrically

The effect of permodified cyclodextrins encapsulation on the photophysical properties of a polyfluorene with randomly distributed electron-donor and rotaxane electron-acceptor units

• Aurica Farcas,
• Ana-Maria Resmerita,
• Pierre-Henri Aubert,
• Flavian Farcas,
• Iuliana Stoica and
• Anton Airinei

Beilstein J. Org. Chem. 2014, 10, 2145–2156, doi:10.3762/bjoc.10.222

• ). This suggests that the intramolecular charge transfer between 1 and 2 units of 1/4 molar ratios is relatively weak. Moreover, the smaller red shift from a dilute solution compared to the solid-state of 4a and 4b polyrotaxanes corroborated the beneficial effect of TMS-β-CD and TMS-γ-CD encapsulations on

Enhancement of efficiency in organic photovoltaic devices containing self-complementary hydrogen-bonding domains

• Rohan J. Kumar,
• Jegadesan Subbiah and
• Andrew B. Holmes

Beilstein J. Org. Chem. 2013, 9, 1102–1110, doi:10.3762/bjoc.9.122

• –vis absorption spectrum of compound 2 exhibited a peak absorbance of 586 nm (Figure 2a), compared with 590 nm for the N-alkylated analogue 1. This transition is assigned to an intramolecular charge-transfer state from the electron-rich triarylamine moiety to the electron-deficient cyanopyridone. The

Thiophene-based donor–acceptor co-oligomers by copper-catalyzed 1,3-dipolar cycloaddition

• Stefanie Potratz,
• Amaresh Mishra and
• Peter Bäuerle

Beilstein J. Org. Chem. 2012, 8, 683–692, doi:10.3762/bjoc.8.76

• -vinylthiophene (276 nm in ethanol) [38]. The second absorption band at 256 nm was assigned to the thiophene ring attached to the 1-position of the triazole. The evidence for intramolecular charge-transfer (ICT) [39] in 5 was investigated in several solvents with different dielectric constants: n-hexane (ε = 1.9

Fluorescent hexaaryl- and hexa-heteroaryl[3]radialenes: Synthesis, structures, and properties

• Antonio Avellaneda,
• Courtney A. Hollis,
• Xin He and
• Christopher J. Sumby

Beilstein J. Org. Chem. 2012, 8, 71–80, doi:10.3762/bjoc.8.7

• calculations that show intramolecular charge transfer character in the lowest excited states for hexaaryl[3]radialene derivatives [42]. In the excited state, rotation about the exocyclic bonds of the cyclopropane ring is also possible. The fluorescence emission of the hexaaryl[3]radialenes, coupled with the

Imidazole as a parent π-conjugated backbone in charge-transfer chromophores

• Jiří Kulhánek and
• Filip Bureš

Beilstein J. Org. Chem. 2012, 8, 25–49, doi:10.3762/bjoc.8.4

• intramolecular charge transfer (ICT) are reviewed. Design, synthetic pathways, linear and nonlinear optical properties, electrochemistry, structure–property relationships, and the prospective application of such D-π-A organic materials are described. This review focuses on Y-shaped imidazoles, bi- and

• devices, etc [1][2][3]. A typical one-component organic D-π-A chromophore consists of a π-conjugated system end-capped with strong electron donors D (e.g. NR2 or OR groups) and strong electron acceptors A (e.g. NO2 or CN groups). This D-π-A arrangement assures efficient intramolecular charge transfer (ICT

• review has attempted to show that 1,3-diazole, imidazole, may act as a robust and stable parent π-conjugated backbone for organic chromophores with intramolecular charge transfer. This synthetically readily accessible five-membered heteroaromate and its push–pull derivatives are currently of high

Ratiometric fluorescent probe for enantioselective detection of D-cysteine in aqueous solution

• Xiao-bo Zhou,
• Wing-Hong Chan,
• Albert W. M. Lee and
• Chi-Chung Yeung

Beilstein J. Org. Chem. 2011, 7, 1508–1515, doi:10.3762/bjoc.7.176

• was developed by us as a cell-permeable, fluorescent, ratiometric sensing probe for the detection of Zn2+ and Cd2+ [35]. Operating according to the intramolecular charge-transfer (ICT) mechanism, complexation of ACAQ with either Cd2+ or Zn2+ triggers a ratiometric change in the emission band of ACAQ

Anthracene appended pyridinium amide–urea conjugate in selective fluorometric sensing of L-N-acetylvaline salt

• Kumaresh Ghosh,
• Tanmay Sarkar and
• Asoke P. Chattopadhyay

Beilstein J. Org. Chem. 2010, 6, 1211–1218, doi:10.3762/bjoc.6.139

• emitting species with life times τ1 = 1 ns (0.02%), τ2 = 4.23 ns (0.02%) and τ3 = 0.62 ps (99.96%) (Figure 7). Among these, the fast decay component 0.62 ps could be attributed to the formation of a hydrogen-bonded short-lived species where presumably intramolecular charge transfer between anthracene and

Syntheses and properties of thienyl-substituted dithienophenazines

• Annemarie Meyer,
• Eva Sigmund,
• Friedhelm Luppertz,
• Gregor Schnakenburg,
• Immanuel Gadaczek,
• Thomas Bredow,
• Stefan-S. Jester and
• Sigurd Höger

Beilstein J. Org. Chem. 2010, 6, 1180–1187, doi:10.3762/bjoc.6.135

• larger delocalized π-system, which lowers the HOMO-LUMO gap as discussed above. The difference density of 12a (Figure 2c) shows that the S0-S1 excitation leads to an intramolecular charge transfer (CT) from the thiophenes to the phenazine part of the molecule. These calculations verify our initial

Donor-acceptor substituted phenylethynyltriphenylenes – excited state intramolecular charge transfer, solvatochromic absorption and fluorescence emission

• Ritesh Nandy and
• Sethuraman Sankararaman

Beilstein J. Org. Chem. 2010, 6, 992–1001, doi:10.3762/bjoc.6.112

• . These results indicate that the fluorescence emission arises from excited state intramolecular charge transfer in these molecules where the triphenylene chromophore acts either as a donor or as an acceptor depending upon the nature of the substituent on the phenyl ring. HOMO–LUMO energy gaps have been

• important especially in the in vivo study of biological samples. Otherwise the background blue emission of the biological samples interferes with the fluorescence sensing. The mechanism of fluorescence sensing often involves excited state intramolecular charge transfer (ICT) [8][9][10][11], photoinduced

• importance. In this class of molecule, the excited state is generally highly polar compared to the ground state due to intramolecular charge transfer from the donor to the acceptor group. The intramolecular charge transfer results in a large dipole moment in the excited state compared to that of the ground

Chromo- and fluorophoric water-soluble polymers and silica particles by nucleophilic substitution reaction of poly(vinyl amine)

• Katja Hofmann,
• Ingolf Kahle,
• Frank Simon and
• Stefan Spange

Beilstein J. Org. Chem. 2010, 6, No. 79, doi:10.3762/bjoc.6.79

• explained by two factors: Firstly, the fluorophore is a very rigid and planar molecule and secondly, the fluorophore contains both strongly electron-withdrawing and electron-donating groups along the axis of the π-conjugated system. Therefore, an efficient intramolecular charge transfer (ICT) system is

[3.3]Dithia-bridged cyclophanes featuring a thienothiophene ring: synthesis, structures and conformational analysis

• Sabir H. Mashraqui,
• Yogesh Sanghvikar,
• Shailesh Ghadhigaonkar,
• Sukeerthi Kumar,
• Auke Meetsma and
• Elise Trân Huu Dâu

Beilstein J. Org. Chem. 2009, 5, No. 74, doi:10.3762/bjoc.5.74

• diversity and complexity of cyclophanes, it is surprising that cyclophanes featuring fused heteronuclei have scarcely been studied [18][19][20]. Lately, we have been exploiting the thieno[2,3-b]thiophene ring, a fused heterocycle towards creating potentially interesting intramolecular charge transfer [21

Synthesis of mesogenic phthalocyanine-C₆₀ donor–acceptor dyads designed for molecular heterojunction photovoltaic devices

• Yves Henri Geerts,
• Olivier Debever,
• Claire Amato and
• Sergey Sergeyev

Beilstein J. Org. Chem. 2009, 5, No. 49, doi:10.3762/bjoc.5.49

• +1.6 V vs. saturated calomel electrode (SCE). These observations, together with UV–vis spectra, suggest the absence of intramolecular charge transfer in the ground state for dyads 2a–d. Preliminary investigation of the dyads 2a–d by polarized optical microscopy (POM) showed that the length of the