Benzothiophene Groups Research Articles

Heavy-atom-free triplet benzothiophene-fused BODIPY derivatives for lipid droplet-specific biomaging and photodynamic therapy.

The twist fusion of a benzothiophene group and the introduction of a 4-methyloxystyryl donor group to the BODIPY core resulted in large spin-orbit coupling values and smaller singlet-triplet energy gaps for the novel infrared absorbed photosensitizers named BSBDP. They show a high reactive oxygen species efficiency exceeding 69% and a fluorescence quantum yield of 23% and are successfully applied in imaging-guided photodynamic therapy in vitro and in vivo.

Theoretical Study of the Photocyclization Reaction-Induced Dual Aggregation-Induced Emission Phenomenon.

Photochromic molecules with aggregation-induced emission (AIE) effects are of great value and prospective in various practical applications. To explore its inherent mechanism, the open isomer ap-BBTE and the closed isomer c-BBTE were chosen to perform the theoretical calculation using the quantum mechanics/molecular mechanics model combined with thermal vibration correlation function formalism. The calculations show that the photocyclization (PC) reaction from ap-BBTE to c-BBTE facilitates an improvement in the AIE effect. It is found that the fluorescence quantum yield (ΦF) enhancement of ap-BBTE is attributed to the restriction of the low-frequency rotational motion of the benzothiophene moiety and the high-frequency stretching vibrations of the C-C bond between the benzothiophene and benzylbis(thiadiazole) vinyl groups after aggregation. For c-BBTE, the increase in ΦF upon aggregation is mainly due to the suppression of the high-frequency stretching vibration of the C-C bond between the benzothiophene and the benzobis(thiadiazole) vinyl groups. In addition, the AIE effect was also enhanced from ap-BBTE to c-BBTE, which is consistent with the experimental phenomenon. The corresponding emission spectrum red-shifted from ap-BBTE to c-BBTE in both dilute solution and the crystalline state due to the improved intramolecular conjugation of c-BBTE. Moreover, the PC reaction from ap-BBTE to c-BBTE easily occurs in an excited state with a low energy barrier transition state by forming a C-C bond between benzothiophene groups effectively in dilute solution. Our calculations provide theoretical guidance for the further rational design of efficient AIE luminogens.

The second coordination sphere effect of benzothiophene groups enhances chain transfer in ethylene (co)oligomerization

The second coordination sphere effect of benzothiophene groups could facilitate the chain transfer in iminopyridyl Ni(ii)/Pd(ii)-catalyzed ethylene (co)oligomerization, in contrast to the phenomenon observed in the corresponding α-diimine system.

Synthesis and Thermal and Phase Behavior of Polysiloxanes with Grafted Dialkyl-Substituted [1]Benzothieno[3,2-b][1]benzothiophene Groups

Synthesis and Thermal and Phase Behavior of Polysiloxanes with Grafted Dialkyl-Substituted [1]Benzothieno[3,2-b][1]benzothiophene Groups

Multicolor Photochromism of Two-Component Diarylethene Crystals Containing Oxidized and Unoxidized Benzothiophene Groups

Preparing mixed crystals composed of two or more components is one of the useful approaches to not only modifying the physical properties and chemical reactivity of molecular crystals but also creating their novel functionality. Here we report preparation and photoresponsive properties of two-component mixed crystals containing photochromic bis(benzothienyl)ethene derivatives that show different colors in the closed-ring forms depending on the oxidation state of the benzothiophene groups. The similarity in the molecular structures of the two diarylethenes, which are different from each other only in the oxidation state of the benzothiophene groups, allowed the formation of two-component mixed crystals by recrystallization from mixed solutions containing the two compounds. Irradiating the mixed crystals with light of appropriate wavelengths induced the selective photoisomerizaion of the two diarylethenes, leading to multicolor photochromic performance, such as colorless, orange, yellow, and red. Such molecular crystals with multiresponsive functions can find potential applications in multistate optical recording and multicolor displays. The present results demonstrate that combining differently oxidized diarylethene derivatives is an effective strategy for preparing multicomponent mixed crystals with finely tuned composition and desired photoresponsive properties.

Second coordination sphere effect of benzothiophene substituents on chain transfer and chain walking in ethylene insertion polymerization

Recently, the α-diimine Ni(II) and Pd(II) catalysts bearing various diarylmethyl substituents on the N-aryl group have drawn much attention. In this work, two bulky diarylmethyl α-diimine Ni(II) catalysts bearing naphthyl and benzothiophene groups were synthesized and employed in ethylene polymerization. The Ni(II) complex bearing naphthyl groups exhibited high activities (ca. 106 g mol−1 h−1) and yielded highly branched (60–70/1000C) polyethylenes with high molecular weights (Mn up to 784.5 kg/mol) in ethylene polymerization. Moreover, this complex exhibited excellent thermal stability at high temperatures, and the polyethylene products obtained demonstrated good mechanical properties (SR up to 59%). Meanwhile, the Ni(II) complex bearing benzothiophene groups displayed high activities (ca. 106 g mol−1 h−1), and generated lightly branched (15–37/1000C) polyethylene with particularly high molecular weights (Mn up to 2017.6 kg/mol) at low temperatures. At high temperatures, the polymerization activity and the molecular weight of the obtained polyethylene decreased significantly. The second coordination sphere effect of benzothiophene substituents is considered to be responsible for the above experimental results.

Unraveling Dual Aggregation-Induced Emission Behavior in Steric-Hindrance Photochromic System for Super Resolution Imaging.

Unprecedented dual aggregation-induced emission (AIE) behavior based on a steric-hindrance photochromic system is presented, with incorporation one or two bulky aryl groups, resulting in different flexibleness. The dual AIE behavior of open and closed isomers can be explained by restriction of intramolecular rotation (RIR), restriction of intramolecular vibration (RIV), and intermolecular stacking. The large bulky benzothiophene causes restricted rotation, enhancing the emission of open form in solution and weak π-π molecular packing, thereby efficiently enhancing the luminescence performance in the solid state. With incorporation of two large bulky benzothiophene groups, BBTE possesses the most outstanding AIE activity, undergoing highly efficient and reversible off-to-on fluorescence in film upon alternating UV and visible light irradiation along with excellent fatigue resistance. The off-to-on fluorescent photoswitch is successfully established in super resolution imaging.

Unraveling Dual Aggregation‐Induced Emission Behavior in Steric‐Hindrance Photochromic System for Super Resolution Imaging

AbstractUnprecedented dual aggregation‐induced emission (AIE) behavior based on a steric‐hindrance photochromic system is presented, with incorporation one or two bulky aryl groups, resulting in different flexibleness. The dual AIE behavior of open and closed isomers can be explained by restriction of intramolecular rotation (RIR), restriction of intramolecular vibration (RIV), and intermolecular stacking. The large bulky benzothiophene causes restricted rotation, enhancing the emission of open form in solution and weak π–π molecular packing, thereby efficiently enhancing the luminescence performance in the solid state. With incorporation of two large bulky benzothiophene groups, BBTE possesses the most outstanding AIE activity, undergoing highly efficient and reversible off‐to‐on fluorescence in film upon alternating UV and visible light irradiation along with excellent fatigue resistance. The off‐to‐on fluorescent photoswitch is successfully established in super resolution imaging.

Turn‐On Fluorescent Photochromic Disulfonylarylthiophenes: Effect of Sulfone Groups on Fluorescence and Conversion

A series of diarylthiophenes containing sulfone groups were synthesized using selective sulfur oxidation of benzothiophene group by meta‐chloroperoxybenzoic acid at room temperature, and their photophysical and chemical properties were studied. These compounds exhibited good photochromic behavior with a good fatigue property under consecutive ultraviolet (UV) and visible irradiation. The ring‐closed form emitted fluorescence upon UV excitation and the wavelength of fluorescence varied depending on the substituent. Compounds 2–5 exhibited high conversion ratios, reaching 95% for compound 5, the benzoyl derivative, under UV irradiation. This high conversion is thought to be due to the lower quantum yield of the ring‐opening reaction compared to the ring‐closing reaction.

Modifying the Chemical Structure of a Porphyrin Small Molecule with Benzothiophene Groups for the Reproducible Fabrication of High Performance Solar Cells.

A porphyrin-based molecule DPPEZnP-BzTBO with bulky benzothiophene groups was designed and synthesized as an electron donor material for bulk heterojunction (BHJ) solar cells. The optimized devices under thermal annealing (TA) and then chloroform solvent vapor anneanling (SVA) for 80 s exhibited an outstanding power conversion efficiencie (PCE) of 9.08%. Contrasted with the smaller thienyl substituted analogues we reported previously, DPPEZnP-BzTBO-based BHJ solar cells exhibited a higher open circuit voltage due to the lower highest occupied molecular orbital energy level. The TA post-treatment of the active layers induced the formation of more crystallized components, and the subsequent SVA provided a driving force for the domain growth, resulting in more obvious phase segregation between the donor and the acceptor in nanoscale. Furthermore, the PCEs kept above 95% upon the further SVA treatment within the time range of 60 to 95 s probably because the bulky benzothiophene groups retard the too quick change of crystallinity, providing a wide processing window for the reproducible device fabrication.

Photochromism of diarylethene derivatives having benzophosphole and benzothiophene groups

Asymmetric diarylethene derivatives having benzophosphole and benzothiophene groups at the aryl moieties were synthesized and their photochromic properties were examined. Three diarylethene derivatives, 1 having benzophosphole and benzothiophene groups, 2 having benzophosphole P-oxide and benzothiophene groups, and 3 having benzophosphole P-oxide and benzothiophene S,S-dioxide groups, were synthesized by appropriately controlled oxidation of benzophosphole and benzothiophene groups. Diarylethenes 1–3 underwent photochromic reactions in acetonitrile as well as in the powder solid state upon alternate irradiation with ultraviolet (UV) and visible light. The closed-ring isomer of diarylethene 3 emitted fluorescence with a quantum yield of 0.05 in acetonitrile solution. The fluorescence quantum yield dramatically increased up to 0.55 in the solid state.

Substituent effects on the photochromic properties of benzothiophene-based derivatives.

Five diarylethene photochromic derivatives, the structures of which incorporate a central benzothiophene unit, a left-hand thiazole group, and a right-hand benzothiophene group, have been prepared. The compound with a thiazole unit with no substituent on the reaction-center carbon atom reveals an unprecedented transformation upon light irradiation. When the 4-position of thiazole is protected by a methyl group, the compounds show high photosensitivity and photochromic properties. In this case, light irradiation affords new compounds with [5]helicene structures featuring the highest redshifted absorption maxima reported to date.

Enhanced Photochemical Sensitivity in Photochromic Diarylethenes Based on a Benzothiophene/Thiophene Nonsymmetrical Structure

AbstractPhotosensitivity of molecules is one of the central subjects of organic photochemistry. In this article, we present how and why a benzothiophene moiety impacts the photochromic quantum yield for the photochemical pericyclic ring closing of the hexatriene moiety. Two compounds were prepared: a symmetrical one incorporating two fluorenylthiophene units, and its corresponding nonsymmetrical partner, where one of the thiophene units was replaced by a benzothiophene group. Interestingly, the latter presents relatively high cyclization quantum yield (0.74), a value close to the largest one so far reported. Based on crystal structures, VT‐NMR data and DFT calculations, we demonstrate that introducing a benzothiophene in the molecular scaffold induces skeleton stiffening by means of CH–π interactions and steric repulsions, and leads to increased population of the reactive conformer in the ambient conditions.

Synthesis and fungicidal activities of novel benzothiophene-substituted oxime ether strobilurins

Twenty-one novel benzothiophene-substituted oxime ether strobilurins, which employed a benzothiophene group to stabilise the E-styryl group in Enoxastrobin (an unsaturated oxime strobilurin fungicide developed by Shenyang Research Institute of Chemical Industry, China) were designed and synthesised. The biological assay indicated that most compounds exhibited good or excellent fungicidal activities, especially against Colletotrichum lagenarium and Puccinia sorghi Schw. In addition, methyl 3-methoxypropenoate oxime ethers and N-methoxy-carbamic acid methyl esters exhibited good in vivo fungicidal activities against Erysiphe graminis, Colletotrichum lagenarium and Puccinia sorghi Schw. under the tested concentrations. Notably, (E,E)-methyl 3-methoxy-2-(2-((((6-chloro-1-(1H-benzo[b]thien-2-yl)ethylidene)amino)oxy)methyl)phenyl)propenoate (5E) exhibited more potent in vivo fungicidal activities against nearly all of the tested fungi at a concentration of 0.39mg/L compared to Enoxastrobin.

Synthesis and Pain Perception of New Analogues of Phencyclidine in NMRI Male Mice

Phencyclidine (PCP, I) and many of its derivatives have demonstrated many pharmacological effects. They interact with a number of neurotransmitter systems within the central nervous system. For example, Phencyclidine is a noncompetitive antagonist of the N-methyl-d-aspartate (NMDA) subtype of the glutamate receptor, and it causes the release and inhibits the reuptake of monoaminergic neurotransmitters, including dopamine, serotonin and norepinephrine. In this study, new thienyl (TCP, II), as well as benzothiophen (BTCP, III) derivatives (IV-VII) were synthesized. The acute and chronic pain activities of these drugs were studied using the tail immersion and formalin tests on mice and the results were compared with PCP, TCP and control groups at dosage of 10 mg/kg. The results indicated that the drug VII produced more analgesic effects on acute chemical pain in formalin test compared with other drugs. In addition, this analgesic effect was remarkably seen for drugs II, VI and VII in chronic pain in the mentioned test in comparison with other drugs. Also, the results showed that acute thermal pain could be diminished by drugs VI, II and I compared with other drugs in tail immersion test. It can be concluded that more analgesic effects of new BTCP analogues (VI and VII) may be concerned with antinociception activities of benzothiophene group and also with binding to cocaine site on the dopamine transporter receptor which seems to be more potent than PCP receptor in decreasing pain.

High-pressure crystallographic and spectroscopic studies on two molecular dithienylethene switches

Single crystals of the dithienylethene compounds, 1,2-bis(2-methylbenzothiophen-3-yl)perfluorocyclopentene 1 and 1,2-bis(2,5-dimethylthiophen-3-yl)perfluorocyclopentene 2 undergo pressure-induced single-crystal to single-crystal phase transitions between 4.45–5.35 GPa and 4.15–5.70 GPa, respectively. For 1, there is a smooth reduction in unit-cell volume of ~20% from ambient pressure to 4.45 GPa, followed by a dramatic reduction in volume that coincides with a 7.7% increase in the b axis length. Above the pressure of 5.38 GPa a smooth volume reduction continues. In contrast, for 2, there is a continuous change in unit-cell volume with an observed space group change from C2/c to P21/c, between the pressures of 4.15 and 5.70 GPa. In the crystals of 1 between 4.45 and 5.38 GPa adjacent molecules slide over each other and the dominant stacking interaction changes from a thiophene⋯thiophene interaction at 4.45 GPa to a benzothiophene⋯benzothiophene interaction at 5.38 GPa and, within each molecule, the benzothiophene groups show a significant reorientation at the phase transition. In 2 there is a loss of molecular symmetry, concomitant with the change in space group, at the phase transition with the asymmetric unit changing from containing half a unique molecule to two independent molecules. The molecules show significant reorientations of their ring systems. The nature of the observed transition in 1 was investigated using solid-state computational methods to prove the superior thermodynamic stability of the high-pressure phase to the lower pressure phase at pressures above 5.38 GPa. Solid state UV-Vis spectroscopy of 1, over the pressure range from ambient to 15.4 GPa showed that the compound displayed piezochromism with a significant red shift in the π–π* absorption band and a colour change in the crystal from colourless to red with increasing pressure.

(E)-2-[1-(1-Benzothio-phen-2-yl)ethyl-idene]-N-phenyl-hydrazinecarboxamide.

The title compound, C17H15N3OS, crystallizes with two unique mol­ecules, denoted 1 and 2, in the asymmetric unit. The two mol­ecules are closely similar and overlay with an r.m.s. deviation of 0.053 Å. Both mol­ecules adopt E configurations with respect to the C=N bonds. The dihedral angles between the benzothio­phene groups and N-bound phenyl rings are 36.36 (9)° for mol­ecule 1 and 29.71 (9)° for mol­ecule 2. The C=N—NH—C(O)NH ethyl­idene–hydrazinecarboxamide units are also reasonably planar, with r.m.s. deviations of 0.061 and 0.056 Å, respectively, for the two mol­ecules. The methyl substituents lie 0.338 (3) and 0.396 (3) Å, respectively, from these planes. The C=N—NH—C(O)NH planes are inclined to the phenyl rings at 13.65 (11) and 15.56 (11)°, respectively, in mol­ecules 1 and 2. This conformation is enhanced by weak intra­molecular C—H⋯O hydrogen bonds between ortho-H atoms of the two phenyl rings and the carbonyl O atoms, which generate S(6) rings in each mol­ecule. In the crystal, pairs of mol­ecules are linked by pairs of inter­molecular N—H⋯O hydrogen bonds into dimers. Alternating dimers are further inter­connected by weak C—H⋯O contacts into zigzag rows along b. The rows are stacked along a by C—H⋯π contacts involving the benzene ring from molecule 2 and the thiophene ring from molecule 1 of adjacent benzothio­phene units.

1-Benzothiophene-2-carbaldehyde 4-ethylthiosemicarbazone

The title compound, C13H15N3S2, crystallizes with two unique mol­ecules, A and B, in the asymmetric unit. These differ principally in that the methyl group of the 4-ethyl­thio­semicarbazone moiety is ordered in mol­ecule A but disordered over two positions with equal occupancies in mol­ecule B. The benzothio­phene group and the semicarbazone unit are inclined at dihedral angles of 11.78 (8)° for mol­ecule A and 8.18 (13)° for mol­ecule B. Weak intra­molecular N—H⋯N inter­actions contribute to the planarity of the semicarbazone units in both mol­ecules and each mol­ecule adopts an E configuration with respect to the C=N bonds. In the crystal structure, mol­ecules form centrosymmetric dimers as a result of N—H⋯S hydrogen bonds, augmented by C—H⋯S inter­actions for mol­ecule A and C—H⋯S inter­actions for mol­ecule B. Weak C—H⋯π inter­actions stack the dimers of both mol­ecules into columns down the a axis.

α,α‐Cyclopentaneglycine Dipeptides Capped with Biaryls as Tachykinin NK2 Receptor Antagonists

The NK(2) receptor belongs to the family of tachykinin neurotransmitters. It has been reported to be involved in several pathological conditions, and selective antagonists are potentially useful drugs for the treatment of asthma, irritable bowel syndrome, cystitis, and depression. Starting from in-house capped dipeptide libraries, we were able to identify a number of molecules with sub-nanomolar binding affinity for the hNK(2) receptor. All were characterized by a rigid core structure with a strong constraint induced by an alpha,alpha-cyclopentaneglycine fragment. Herein we report the further elaboration of three initial basic structures. The planar benzothiophene group was substituted with a series of biphenyl and heterobiphenyl moieties that are well tolerated in terms of receptor affinity. The new compounds also maintained good antagonist potency in an in vitro functional assay, and a number of them showed significant in vivo activity after intravenous administration in our guinea pig model.

Improvement of Luminescence Quantum Efficiency by Intermolecular Interaction

Due to their unique photophysical properties, highly fluorescent compounds are currently of great interest for material science applications, such as photo-electronics, organic light-emitting diodes (OLEDs) and chemical sensors. In particular, efforts have focused on the improvement of fluorescence quantum yields (ΦF), since the ΦF of emitting materials and the device efficiency in OLEDs are generally related. For this purpose, several approaches have been suggested including the attachment of anthracene and/or pyrene units having high ΦF to the molecular framework, the extension of π-conjugation and the introduction of electronwithdrawing groups (F, CN, etc) as substituents. Among such approaches, the introduction of electron-withdrawing groups to the molecular backbone has received greater attention, because the molecules containing these groups have shown unusual and high fluorescence quantum efficiency through the intermolecular interactions. Such phenomenon is often called aggregation induced emission (AIE). During our ongoing efforts on the development of luminescent materials, we have observed that fluoreneand anthracene-based compounds linked by a perfluorocyclopentene core unit have high fluorescence quantum efficiency as compared to 9,10-diphenylanthracene (DPA). Our interest in the synthesis of highly fluorescent materials containing a perfluorocyclopentene core unit, which can provide binding sites for hydrogen atoms of adjacent molecules via intermolecular interactions, has prompted us to investigate the syntheses and photophysical properties of their derivatives. Here, we report on the syntheses, crystal structure and optical properties of a series of V-shaped molecules containing the linker of an electron-withdrawing moiety. In addition, the effect of electron-withdrawing substituents on fluorescence quantum efficiency has been systematically evaluated at the molecular level. Scheme 1 outlines the synthesis of the series of benzothiophene derivatives. Compound 1 and 2 were prepared by the addition of octafluorocyclopentene to the corresponding lithiated compound, prepared from the reaction of a small excess of n-BuLi and the bromoarene at −78 C. The standard work up and crystallization from CH2Cl2/hexane produces compounds as colorless or pale yellow solids in moderate yields (45-55%). In addition, to evaluate the effect of a perfluorocyclopentene ring on structural features and photoluminescence, we have synthesized an aromatic analogue of compound 3, through Pd-mediated Suzuki coupling. The structures of 1-3 have been characterized by H-NMR, C-NMR and elemental analyses, including Xray diffraction analysis of 2. Yellow crystals of 2 that were suitable for X-ray analysis were obtained by the slow evaporation in CH2Cl2 and hexane. The crystal structures and selected bond lengths and angles of 1 are presented in Figure 1. As shown in the Figure, two benzothiophene groups connected by the hexafluorocyclopentene linker are twisted with respect to each other. Note that the hexafluorocyclopentene linker and one (S1 ring) of two benzothiophene rings are arranged a nearly coplanar manner with a dihedral angle of 5.44, while the other (S2 ring) is highly tilted toward the hexafluorocyclopentene core with a dihedral angle of 71.96. This observation is very uncommon in diarylethene derivatives