Functionalized Fused Thiophenes: A New Class of Thermally Stable and Efficient Second-Order Nonlinear Optical Chromophores

Rao, Varanasi Pushkara; Wong, Kwan-Yee K.; Jen, Alex K.‐Y.; Drost, Kevin J.

doi:10.1021/cm00048a004

Cited by 55 publications

(35 citation statements)

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“…Oligophenylenes attain a rapid saturation beyond the terphenyl unit, whereas oligothiophenes have a strong tendency to increase µβ(0) with increasing number of thiophene units. Aside from the electron transmission efficiency, another merit of oligothiophenes is their inherent stability from which thiophene-based D-A chromophores should benefit [19,20]. Some of us have recently reported on the synthesis of several donor-acceptor end-capped oligothiophenes bearing different 5-dialkylamino (D) and 5'-dicyanovinyl or 5'-tricyanovinyl (A) electroactive end groups with the scope of searching new solvatochromic dyes which could act as suited probes for the determination of solvent polarity or as materials with potential applications in NLO ( Figure 1) [21].…”

Section: Introductionmentioning

confidence: 99%

Invited Paper

Oliva¹,

Delgado²,

Casado³

et al. 2007

Computing Letters

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series of push-pull chromophores built around thiophene-based . π-conjugating spacers and bearing various types of amino-donors and cyanovinyl-acceptors have been analyzed by means of UV-Vis- NIR spectroscopic measurements. Density functional theory (DFT) calculations have also been performed to help the assignment of the most relevant electronic features and to derive useful information about the molecular structure of these NLO-phores. The effects of the donor/acceptor substitution in the electronic and molecular properties of the .π -conjugated spacer have been addressed. The effectiveness of the intramolecular charge transfer (ICT) has also been tested as a function of the nature of the end groups (i.e., electron-donating or electron-withdrawing capabilities).

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Section: Introductionmentioning

confidence: 99%

Invited Paper

Oliva¹,

Delgado²,

Casado³

et al. 2007

Computing Letters

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“…Application of the complete thermal protocol, while time consuming, provides useful data for prediction of the utility of NLO chromophores in high temperature poled polymer applications. While it is clear from our studies that there is an inverse relationship between chromophore thermal stability and molecular nonlinearity as determined by electric field induced second harmonic generation studies, the relationship varies with structure, and reasonable compromises of the thermal stability-nonlinearity tradeoff may be achieved (9)(10)(11)(12)(13)(14)(15)(16)(17). In this regard, we have observed that for amino donor substituents, higher thermal stabilities are always observed for N-aryl substituents than for hydrogen or alkyl substitution.…”

Section: Thermal Stability Of Nlo Chromophoresmentioning

confidence: 80%

High-Temperature Nonlinear Optical Chromophores and Polymers

Miller

Burland

Jurich

et al. 1997

ACS Symposium Series

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Poled polymers for fully integrated modulator and switching applications will require orientational stability under device operating conditions and thermal stability of the chromophores and polymers during poling and integration. The latter may require heating to 250°C or more for brief periods. We describe here the preparation of a number of NLO polyimide derivatives which meet these thermal requirements. Derivatives containing the NLO chromophore donor substituents embedded in the polymer main chain show exceptional thermal and orientational stability. We also describe preliminary results on the efficient photoassisted electric field poling of high Tg azo-containing polymers at room temperature. This process may alleviate some of the difficulties inherent to poling at very high temperatures.Organic nonlinear optical materials (NLO) have attracted attention recently as potentially fast and efficient components of optical communication and computing systems. Although they have been studied in many forms including crystals, clathrates, organic glasses, sol-gel composites, vapor deposited films, Langmuir-Blodgett structures, etc., poled polymer films provide the best opportunity for near-term applications, particularly in the area of electro-optic modulators and switches (7). In this regard, there are two possible scenarios: (i) external applications separate from the silicon device circuitry and (ii) My integrated electro-optic modulators and switches. Each of these configurations, while sharing certain common characteristics, differ significantly in the thermal stability requirements. For purposes of discussion, we have designated the applications as type I and type II respectively. For each application, long term stability of the polymers (chemical, oxidative and orientational) will be required at operating temperatures which may vary between 80-125°C depending on the configuration and application. Orientational stability in poled 100

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“…Furthermore, this cistrans isomerization results in a local concentration of rc-electron density, which in turn favors a reaction with electrophiles such as singlet oxygen. To eliminate the thermal instability associated with olefinic linkages, we designed a new class of materials (22) lacking olefinic bonds, such as 12, and also a set of compounds based on bithiophenes and fused-thiophenes Q3 and 14) in Table IV. In these compounds, the ketendithioacetal group (9) serves as the electrondonor and the tricyanovinyl group as the electron-acceptor.…”

Section: Tradeoffs Between Thermal Stability and Molecular Nonlinearitymentioning

confidence: 99%

Highly Efficient and Thermally Stable Second-Order Nonlinear Optical Chromophores and Electrooptic Polymers

Jen¹,

Rao²,

Chandrasekhar

1995

ACS Symposium Series

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Organic polymeric electro-optic (E-O) materials have attracted significant attention because of their potential use as fast and efficient components of integrated photonic devices (1,2). However, the practical application of these materials in optical devices is somewhat limited by the stringent material requirements imposed by the device design, fabrication processes and operating environments. Among the various material requirements, the most notable ones are large electro-optic coefficients (r 33 ) and high thermal stability (3). The design of poled polymeric materials with high electro-optic activity (r33) involves the optimization of the percent incorporation of efficient (large βµ) second order nonlinear optical (NLO) chromophores into the polymer matrices and the effective creation of poling-induced non-centrosymmetric structures. The factors that affect the material stability are a) the inherent thermal stability of the NLO chromophores, b) the chemical stability of the NLO chromophores during the polymer processing conditions, and c) the long-term dipolar alignment stability at high temperatures. Although considerable progress has been made in achieving these properties (4), organic polymeric materials suitable for practical E-O device applications are yet to be developed. This chapter highlights some of our approaches in the optimization of molecular and material nonlinear optical and thermal properties. Push-Pull Heteroaromatic Stilbenes: Experimental and Theoretical StudiesFor some time, the EniChem group has been studying thiophene incorporated donor-acceptor (D-A) compounds for second order nonlinear optical applications (5-9). Our initial studies focused on the replacement of the benzene rings of the well known N,N-diethylamino-4-nitrostilbene (DANS, 1) with thiophene moieties (5). The rationale was that the lower resonance energy of thiophene relative to benzene should reduce the aromatic derealization and thereby increase the electronic transmission between donor and acceptor substituents resulting in an increase of p. Indeed, the experimental EFISH studies (1.907 u.m, dioxane solvent) revealed that the Pp. value of 2 was significantly higher than that of 1 (Table I). This result in conjunction with the comparable dipole moments of 1 (7.3 debye) and 2 (7.1 debye) demonstrated that the increase in pu, upon thiophene substitution is solely due to the increase in first-order hyperpolarizability, p.

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Functionalized Fused Thiophenes: A New Class of Thermally Stable and Efficient Second-Order Nonlinear Optical Chromophores

Cited by 55 publications

References 0 publications

Invited Paper

Invited Paper

High-Temperature Nonlinear Optical Chromophores and Polymers

Highly Efficient and Thermally Stable Second-Order Nonlinear Optical Chromophores and Electrooptic Polymers

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