Synthesis of 5-aryl-5´-formyl-2,2´-bithiophenes as new precursors for nonlinear optical (NLO) materials

A series of formyl-substituted 5-aryl-2,2´-bithiophenes 5 were synthesized using two different methods: Vilsmeier-Haack-Arnold reaction (VHA) or through Suzuki coupling. The synthesis of compounds 5 through the Vilsmeier-Haack-Arnold reaction, starting from inexpensive and easily available precursors such as acetophenones, gave the title compounds in low yields after four reaction steps. On the other hand Suzuki coupling of functionalized aryl boronic acids 7 and the 5-bromo-5´-formyl-2,2´-bithiophene 6 gave compounds 5 in good yields in only one step.Fundação para a Ciência e a Tecnologia (FCT

Synthesis and characterization of novel efficient and thermally stable 2-aryl-5-dicyanovinylthiophenes and 5-aryl-5´-dicyanovinyl-2,2´-bithiophenes as potentially promising nonlinear optical (NLO) materials

Two series of dicyanovinyl-substituted compounds namely 2-aryl-5-dicyanovinyl-thiophenes 4 and 5-aryl-5´-dicyanovinyl-2,2´-bithiophenes 6 were synthesized through Knoevenagel condensation of the corresponding 2-aryl-5-formyl-thiophenes 3 and 5-aryl-5´-formyl-2,2´-bithiophene 5 precursors. On the other hand, precursors 3 were prepared through the Vilsmeier-Haack-Arnold reaction (VHA) starting from inexpensive and easily available precursors such as acetophenones. This method produced the title compounds in higher yields than the recently reported synthesis via Suzuki coupling of functionalized aryl boronic acids with 5-bromo-2-formyl-thiophene. Electrochemical studies and characterization of the optical (linear and nonlinear), and thermal properties for compounds 5-6 indicate that, good nonlinearity is complemented by exceptional thermal stability for chromophores 6, making them potential candidates for several optoelectronic applications such as solvatochromic probes and nonlinear optical materials.Fundação para a Ciência e a Tecnologia (FCT) - PTDC/QUI/66251/2006, programa “Acções Integradas Luso-Francesas/CRUP-CP

Theoretical and experimental studies of aryl-bithiophene based push-pull pi-conjugated heterocyclic systems bearing cyanoacetic or rhodanine-3-acetic acid acceptors for SHG nonlinear optical applications

A series of push-pull aryl-bithiophene based systems 2-3 were designed and synthesized in order to understand how structural modifications influence the electronic, linear and nonlinear optical properties. The push-pull conjugated chromophores 2-3 bear a bithiophene spacer conjugated with a phenyl ring functionalized with N,N-dialkylamino electron-donor groups together with cyanoacetic or rhodanine-3-acetic acid acceptor groups. Theoretical (DFT calculations) and experimental studies were carried out to obtain information on conformation, electronic structure, electron distribution, dipolar moment, and molecular nonlinearity response of the push-pull bithiophene derivatives. This multidisciplinary study revealed that chromophore 2e exhibits the highest value for hyperpolarizability beta (10440 × 10-30 esu) due to the strong electron donating ability of the N,N-diethylamino group, and the ethyne linker that not only lengthens the pi- conjugation path but also grants less distortion to the system.Thanks are due to Fundação para a Ciência e Tecnologia (FCT) for a PhD grant to S. S. M. Fernandes (SFRH/BD/87786/2012) and FEDERCOMPETE for financial support through the CQ/UM (Ref. UID/QUI/ 00686/2013 and UID/QUI/0686/2016). The NMR spectrometer Bruker Avance III 400 is part of the National NMR Network and was purchased within the framework of the National Program for Scientific Reequipment, contract REDE/1517/RMN/2005 with funds from POCI 2010 (FEDER) and FCT. The pulsed laser system was acquired within the framework of the grant (PTDC/CTM/105597/2008) from the Fundação para a Ciência e Tecnologia (FCT) with funding from FEDERCOMPETE. This work was also supported by the Associated Laboratory for Sustainable Chemistry - Clean Processes and Technologies - LAQV which is financed by Portuguese national funds from FCT/MEC (UID/ QUI/50006/2013) and co-financed by the ERDF under the PT2020 Partnership Agreement (POCI-01-0145-FEDER–007265).info:eu-repo/semantics/publishedVersio

3-[(2-Formyl­thio­phen-3-yl)(hy­droxy)meth­yl]thio­phene-2-carbaldehyde

In the title compound, C11H8O3S2, the dihedral angle between the mean planes of the two thio­phene rings is 65.10 (10)°. Intra­molecular C—H⋯O inter­actions form S(6) and S(7) ring motifs. In the crystal, chains along the a axis are formed by C—H⋯O inter­actions. Adjacent chains are connected into a three-dimensional network by C—H⋯O and O—H⋯O inter­actions

Dual Photosensitive Polymers with Wavelength-Selective Photoresponse

Polyurethane thin films that photopolymerize and photodegrade upon exposure to light of different wavelengths are presented. The chromic response is based on two caged monomers with the ability to be activated or photocleaved with different wavelengths under single and two-photon excitation. This material represents a dual photoresist with "positive" and "negative" tone contained in a single resist formulation and with the ability to generate complex 2D and 3D patterns.The authors thank the DFG-ANR bilateral funding program for financial support (ANR- 09-BLAN-0426–01 and DFG CA880/3–1). Andreas Best, Dr. K. Koynov and Dr. F. Laquai (MPIP Mainz) are gratefully acknowledged for their help with the two-photon exposure

Synthesis, fluorescence and two-photon absorption properties of push-pull 5-aryl[3,2-b]thienothiophene derivatives

Three series of novel push-pull 5-aryl[3,2-b]thienothiophene derivatives functionalized with potent electron-withdrawing terminal moieties) were synthesized in moderate to excellent yields through Suzuki coupling followed by Knoevenagel condensation. These novel chromophores combine intense absorption in the near-UV down to the orange visible region in relation with a strong intramolecular charge transfer transition. By combining strong donor and acceptor, large fluorescence quantum yield are achieved as well as large two-photon absorption responses. Interestingly, due to the improved rigidity and electronic delocalization provided by the thienothiophene moiety (compared to the bis-thiophene one) larger one- and two-photon brightness values are achieved. As a result, a library of new fluorescent dyes showing enhanced brightness (up to and tunable fluorescence (ranging from blue to the NIR region) has been obtained which offer interesting promises for bioimaging applications.FCT, FEDER, QREN PEst-C/QUI/UI0686/2013 (FCOMP-01-0124-FEDER-037302

Fluorescence and two-photon absorption of push-pull aryl(bi)thiophenes: structure-property relationships

Special Issue in honor of Jean-Pierre SauvagePhotophysical and TPA properties of series of push-pull aryl(bi)thiophene chromophores bearing electron-donating (D) and electron-withdrawing (A) end-groups of increasing strength are presented. All compounds show an intense Intramolecular Charge Transfer (ICT) absorption band in the visible region. Increasing the D and/or A strength as well as the length of the conjugated path induces a bathochromic and hyperchromic of the absorption band as reported for analogous push-pull polyenes. Yet, in contrast with corresponding push-pull polyenes, a significant increase in fluorescence is observed. In particular, chromophores built from a phenyl-bithienyl conjugated path and bearing strong D and A end-groups were found to combine very large one and two-photon brightness as well as strong emission in the red/NIR region. These molecules hold promises as biphotonic fluorescent probes for bioimaging.Fundação para a Ciência e a Tecnologia (FCT

Molybdenum complexes bearing thiophenic or- arylthiophenic groups : synthesis, electrochemical, spectroscopic and nonlinear optical properties

A series of complexes trans-[FMo(N=NCHL)(dppe)2][BF4] (L = (bi)thienyl or arylthienyl), were synthesized and fully characterized by 1H, 13C, 31P NMR, IR and UV–Vis spectroscopies. The electronic spectra and electrochemical behavior of the complexes were investigated. The electronic absorption spectra of these complexes display a broad low-energy band in the visible region attributable to metal-to ligand charge transfer (MLCT) transitions. The electron conjugated effect with the heterocyclic nucleus led to a notable improvement of visible light absorption and marked changes in the electrochemical behavior. The hyperpolarizabilities beta of the synthesized compounds were evaluated using the hyper-Rayleigh scattering technique.Fundação para a Ciência e a Tecnologia (FCT

Photoactivatable drugs for nicotinic optopharmacology

Photoactivatable pharmacological agents have revolutionized neuroscience, but the palette of available compounds is limited. We describe a general method for caging tertiary amines by using a stable quaternary ammonium linkage that elicits a red shift in the activation wavelength. We prepared a photoactivatable nicotine (PA-Nic), uncageable via one- or two-photon excitation, that is useful to study nicotinic acetylcholine receptors (nAChRs) in different experimental preparations and spatiotemporal scales

Synthèse et caractérisation des propriétés optiques de structures donneur-accepteur conjuguées par un système hétérocyclique central

The synthesis of organic compound as components of materials for nonlinear optics has been the focus of many researches because of their potential uses in the fields of optical communications, information process, imagery ... Most often, the molecules with strong hyperpolarizabilitie [bêta] values incorporate a pair of donor-acceptor groups connected via a [pi] -conjugated system. Those containing heterocycles motifs received considerable attention in the field of nonlinear optics due to their relative facility of preparation. We are interested in designing of new molecules with the structure previously described. The structural changes have focused on the donor group (alkoxy, dialkylamino carried by an aromatic ring), the acceptor group (dicyanovynil, cyanoacrylic acid and thiobarbituric acid) and [pi]-conjugated system (thiophene, thieno[3,2-b]thiophene and bithiophene). The optical properties of these compounds have been studied and we have established some links between some structural changes and optical properties. The high values of [bêta] obtained clearly show the potential of compounds prepared and used to explore other structural modifications to improve these valuesLa synthèse de chromophores organiques comme composants de matériaux pour l'optique non-linéaire a été le point central d'un grand nombre de recherches, en raison de leur utilisation potentielle dans les domaines des communications optiques, du traitement de l'information, de l'imagerie? Le plus souvent, les molécules possédant de fortes valeurs d'hyperpolarisabilité [bêta] sont constituées d'un couple de groupements donneur-accepteur connecté par le biais d'un système [pi]-conjugué. Celles comportant des hétérocycles comme motifs centraux ont reçu une attention considérable dans le domaine de l'optique non-linéaire en raison de leur relative facilité de préparation et de la variation de leur degré de polarité. A ce titre, nous nous sommes intéressés à la conception de nouvelles molécules ayant la structure précédemment décrite. Les variations structurales ont porté sur le groupement donneur (alkoxy, dialkylamino porté par un cycle aromatique), le groupement accepteur (dicyanovinyle, acide cyanoacrylique et acide thiobarbiturique) et le système [pi]-conjugué (thiophène, thiéno[3,2-b]thiophène et bithiophène). Les propriétés optiques de ces composés ont été étudiées et ont permis d'établir quelques liens entre certaines modifications structurales et les propriétés optiques. Les fortes valeurs de [bêta] obtenues montrent clairement le potentiel des composés préparés et permettent d?envisager d?autres modifications structurales afin d'encore améliorer ces valeur