Pyrene appended terpyridine derivatives as electrochemiluminescence material for OLEDs: Characterization of photo-physical, thermal and electrochemical properties

Three new terpyridine appended pyrene derivatives (Pyr-Tp, Pyr-Ph-Tp, and Pyr-Bp-Tp) have been synthesized by condensation and Suzuki-Miyaura reaction. The photo-physical, electro-chemical and thermal properties of these compounds have been investigated in detail. DFT studies have been carried out to understand the structure-property relationships at the molecular level. Synthesized fluorophores displayed high quantum yield (70-96%) of fluorescence due to triplet to singlet intramolecular energy transfer, delayed fluorescence and positive solvatochromism indicating the presence of intra-molecular charge transfer excited state. In addition, they have high thermal decomposition temperature (Td: 390-450°C), melting temperature (Tm: 180-220°C) and further with suitable oxidation and reduction potentials makes them favourable molecules for OLED fabrications.

Experimental study of end-capped acceptors influencing the photo-physical, electrochemical and thermal parameters of A-D-π-D-A type small molecular electron donors

385-392We have designed A-D-π-D-A type three new small molecular donor materials denoted as FD-IND, FD-DCV and FD-NBR, which have been synthesised and their photo-physical, electrochemical and thermal properties explored. The synthesised materials have fluorene as “π-spacer,” dithieonopyrrole as “Donor” (D) and various “Acceptor” (A) units are 1,3-indanedione (IND), dicyanovinylene (DCV) and N-butyl rhodanine (NBR). All these three materials have good solubility (~30 mg/mL) in most common organic solvents and have relatively broad absorption in the visible region covering the range of 300-650 nm with two primary absorption bands. The absorption bands located at shorter wavelength region are ascribed to a localized aromatic π-π* transition of the A-D-π-D-A system, while the bands at longer wavelength are mainly attributed to an ICT transition. All the compounds exhibit excellent thermal stabilities in the range of 260-373°C. Cyclic voltammetry data provided HOMO values as −5.26, −5.32 and −5.32 eV for FD-NBR, FD-DCV and FD-IND respectively. LUMO values estimated from HOMO values and optical band gap are −3.27, −3.22 and −3.37 eV for FD-NBR, FD-DCV and FD-IND respectively. Therefore, these are potential molecules for organic solar cells

Experimental study of end-capped acceptors influencing the photo-physical,electrochemical and thermal parameters of A-D-π-D-A type small molecularelectron donors

We have designed A-D-π-D-A type three new small molecular donor materials denoted as FD-IND, FD-DCV andFD-NBR, which have been synthesised and their photo-physical, electrochemical and thermal properties explored.The synthesised materials have fluorene as “π-spacer,” dithieonopyrrole as “Donor” (D) and various “Acceptor” (A) unitsare 1,3-indanedione (IND), dicyanovinylene (DCV) and N-butyl rhodanine (NBR). All these three materials have goodsolubility (~30 mg/mL) in most common organic solvents and have relatively broad absorption in the visible regioncovering the range of 300-650 nm with two primary absorption bands. The absorption bands located at shorter wavelengthregion are ascribed to a localized aromatic π-π* transition of the A-D-π-D-A system, while the bands at longer wavelengthare mainly attributed to an ICT transition. All the compounds exhibit excellent thermal stabilities in the range of 260-373°C.Cyclic voltammetry data provided HOMO values as −5.26, −5.32 and −5.32 eV for FD-NBR, FD-DCV and FD-INDrespectively. LUMO values estimated from HOMO values and optical band gap are −3.27, −3.22 and −3.37 eV forFD-NBR, FD-DCV and FD-IND respectively. Therefore, these are potential molecules for organic solar cells

Pyrene appended terpyridine derivatives as electrochemiluminescence material for OLEDs: Characterization of photo-physical, thermal and electrochemical properties

1564-1574Three new terpyridine appended pyrene derivatives (Pyr-Tp, Pyr-Ph-Tp, and Pyr-Bp-Tp) have been synthesized by condensation and Suzuki-Miyaura reaction. The photo-physical, electro-chemical and thermal properties of these compounds have been investigated in detail. DFT studies have been carried out to understand the structure-property relationships at the molecular level. Synthesized fluorophores displayed high quantum yield (70-96%) of fluorescence due to triplet to singlet intramolecular energy transfer, delayed fluorescence and positive solvatochromism indicating the presence of intra-molecular charge transfer excited state. In addition, they have high thermal decomposition temperature (Td: 390-450°C), melting temperature (Tm: 180-220°C) and further with suitable oxidation and reduction potentials makes them favourable molecules for OLED fabrications

The search for the 'next' euphoric non-fentanil novel synthetic opioids on the illicit drugs market: current status and horizon scanning

Purpose: A detailed review on the chemistry and pharmacology of non-fentanil novel synthetic opioid receptor agonists, particularly N-substituted benzamides and acetamides (known colloquially as U-drugs) and 4-aminocyclohexanols, developed at the Upjohn Company in the 1970s and 1980s is presentedMethod: Peer-reviewed literature, patents, professional literature, data from international early warning systems and drug user fora discussion threads have been used to track their emergence as substances of abuse.Results: In terms of impact on drug markets, prevalence and harm, the most significant compound of this class to date has been U-47700 (trans-3,4-dichloro-N-[2-(dimethylamino)cyclohexyl]-N-methylbenzamide), reported by users to give short-lasting euphoric effects and a desire to re-dose. Since U-47700 was internationally controlled in 2017, a range of related compounds with similar chemical structures, adapted from the original patented compounds, have appeared on the illicit drugs market. Interest in a structurally unrelated opioid developed by the Upjohn Company and now known as BDPC/bromadol appears to be increasing and should be closely monitored.Conclusions: International early warning systems are an essential part of tracking emerging psychoactive substances and allow responsive action to be taken to facilitate the gathering of relevant data for detailed risk assessments. Pre-emptive research on the most likely compounds to emerge next, so providing drug metabolism and pharmacokinetic data to ensure that new substances are detected early in toxicological samples is recommended. As these compounds are chiral compounds and stereochemistry has a large effect on their potency, it is recommended that detection methods consider the determination of configuration

Delayed fluorescence based phenanthroimidazoles as OLED emitters having electron transporting properties

229-240Three new phenanthroimidazole derivatives have been synthesised and their optical, electrochemical, and thermal properties evaluated with the purpose of using them for making of possible OLED materials. Synthesised compounds have fluorescence quantum yields up to 73%, robust thermal properties with high decomposition temperatures between 400 to 430°C and glass transition temperature of between 115 to 122°C. The delayed fluorescence observed is due to intra-molecular triplet to singlet energy transfer. The electrochemical properties together with optical properties and in particular the delayed fluorescence properties make them potential electron transporting cum blue emitting materials for OLEDs

Synthesis, characterization and antimicrobial activity of some new Baylis-Hillman derived benzothiazolo pyrimidinone derivatives

217-227<span style="font-size:10.0pt;font-family: " times="" new="" roman";mso-fareast-font-family:"times="" roman";mso-bidi-font-family:="" mangal;mso-ansi-language:en-us;mso-fareast-language:en-us;mso-bidi-language:="" hi"="" lang="EN-US">A series of Baylis–Hillman derived 22 new benzothiazolo pyrimidinone derivatives have been synthesized from Baylis-Hillman acetates and 2-amino benzothiazole under neat conditions with high yields. All the newly synthesized compounds have been characterized by their spectral data and evaluated for their antibacterial and antifungal activity. Among the 22 new benzothiazolo pyrimidinone compounds, 3o which is having fluoro group at ortho position of phenyl ring has shown excellent activity against gram-positive as well as gram-negative bacteria. Compounds 3f, <b style="mso-bidi-font-weight: normal">3m, 3q exhibit good antibacterial activity compared to the remaining compounds. Among all the compounds, 3o has good antifungal activity and compounds 3f, 3h,<b style="mso-bidi-font-weight: normal"> 3k, 3m, 3q and 3s exhibit comparable antifungal activity. The presence of bezothiazolo pyrimidinone moiety along with-F,-Cl,-CF3 and isopropyl substituent groups on the phenyl ring plays a significant role towards antimicrobial activity.</span

Wavelength dependent regioselective E→Z isomerization of 9-anthryldiene derivatives

1833-18479-Anthryldiene derivatives 1-5 are synthesized to study E→Z photoisomerization. Photoisomer composition upon direct excitation, and triplet-sensitized isomerization are determined. Quantum yield of isomerization, quantum yield of fluorescence and fluorescence life times are determined for these compounds. Interestingly, upon direct excitation the anthryldiene derivatives 1-3 carrying electron withdrawing end groups (EWG) displayed wavelength dependent regioselective E→Z isomerization from the singlet excited state. Triplet sensitization studies revealed that these anthryldiene derivatives undergo Z→E isomerization and not E→Z isomerization. The dual fluorescence observed for 1, 2, 3 and 2E, 4Z-1, indicates the involvement of two different emissive states. The fluorescence solvatochromism displayed by 1, 2, 3 and 2E, 4Z-1 is a clear indication of the involvement of a highly polarized/charge transfer singlet-excited state and the same is involved in the isomerization process. Fluorescence lifetimes measured for these compounds displayed bi-exponential behavior supporting the presence of two emissive states. A mechanism for photoisomerization is suggested

Synthesis and Ultrafast Dynamics of a Donor–Acceptor–Donor Molecule Having Optoelectronic Properties

The use of push–pull molecules having donor (D) and acceptor (A) parts arranged in different shapes are being widely studied for application in various optoelectronic devices. In this study three covalently linked D–A–D molecules containing three different carbazole derivatives as donor, anthracene as acceptor, and thiophene as spacer have been synthesized and characterized. A detailed stepwise study has been carried out using anthracene, thiophene–anthracene, and carbazole–thiophene–anthracene derivatives so as to indicate the role of each moiety in the molecule. Steady state fluorescence, time-resolved fluorescence, transient absorption, and cyclic voltammetric methods have been employed to understand the intramolecular charge separation (CS) and charge recombination (CR) dynamics in solvents of different polarity. The thermodynamic free-energy obtained by measuring the redox potential and singlet state energy suggested the possibility of electron transfer from the excited singlet state of carbazole moiety to the anthracene entity. Steady state and time-resolved fluorescence studies showed fluorescence quenching of anthracene moiety upon addition of thiophene while highly efficient fluorescence quenching of anthracene moiety was observed on addition of carbazole derivatives. Femtosecond transient absorption studies confirmed the electron transfer to be the mechanism of fluorescence quenching, in which formation and recombination dynamics of electron-transfer products, anthracene radical anion and carbazole radical cation, were analyzed. The rate of charge separation, <i>k</i>_CS, was found to be very high for all the three molecules, and it was on the order of 10¹⁰–10¹¹ s^–1, while the rate of charge recombination, <i>k</i>_CR, was observed to be much slower, and it was on the order of 10⁸–10⁹ s^–1. The stepwise structure–property relationship leading to the efficient charge separated state established in the systems studied would help in the improved design of optoelectronic materials that use these moieties

Synthesis and antischistosomal activity of new furoxan derivatives of praziquantel

112-119A series of new furoxan derivatives of praziquantel have been synthesized and evaluated for antischistosomal activity. The newly synthesized hybrid compounds have structural modifications at amide and aromatic rings and thus offer broad structure-activity variations. All the compounds have been tested against adult as well as immature Schistosoma mansoni. Compounds 15 and 18 show moderate activity against adult schistosomes. On immature worms, only compound 15 shows substantial activity whereas the standard drug PZQ is practically inactive at this stage