Frédéric Perreault | Université de Sherbrooke (University of Sherbrooke) (original) (raw)

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Papers by Frédéric Perreault

Research paper thumbnail of Crystal structure of liquid-crystalline compounds possessing a 1,4-diaryl-1-buten-3-yne rigid core

... designed from an enyne (1,4-diaryl-1-buten-3-yne) rigid core inserted between alkoxy chains w... more ... designed from an enyne (1,4-diaryl-1-buten-3-yne) rigid core inserted between alkoxy chains was found to exhibit a rich thermal polymorphism; some compounds revealed up to four distinct mesophases [11. Soldera , A. , Beaudoin , M.-A. , O'Brian , G. , & Lessard , J. ( 2005 ). ...

Research paper thumbnail of Multi-scale approach to the design of ferroelectric liquid crystals for NLO applications

Comparing data from ab initio calculations on a molecule and experimental measurements in the mat... more Comparing data from ab initio calculations on a molecule and experimental measurements in the material is not straightforward since environment and bulk symmetry have to be considered. To design compounds with performing properties, a multi-scale approach is proposed, combining molecular modeling with experimental and theoretical investigations. This procedure is applied to the design of new ferroelectric liquid crystals for NLO

Research paper thumbnail of Theoretical Design of the Molecular Structure of Bent-Core Mesogens with Large Second-Order Nonlinear Optical Properties

The Journal of Physical Chemistry C, 2012

ABSTRACT The first hyperpolarizability of two series of mols. with bent-shaped structures has bee... more ABSTRACT The first hyperpolarizability of two series of mols. with bent-shaped structures has been calcd. at the ab initio level. The two series consist of carboxyl derivs. for which some mols. are known to exhibit banana phases and of their sulfinate homologues that have not been synthesized yet. The final purpose is to reveal the relevance or not in synthesizing these latter mols. The strategy is based on reporting the effect of the positions of donor and acceptor groups on the central benzene ring on the structural parameters and on the first hyperpolarizabilities. It is shown that in the sulfinate series the larger first hyperpolarizabilities are incompatible with efficient geometrical character while for the carboxyl series, the opening angle between the mol. arms is typical of banana-shaped mols. but the first hyperpolarizability is only slightly enhanced. Calcns. thus reveal that the sulfinate series does not need to be synthesized, whereas they show that our approach can be naturally applied to the development of new bent-shaped mols. for nonlinear optical applications. [on SciFinder(R)]

Research paper thumbnail of Theoretical design of sulfinate-based ferroelectric liquid crystals displaying second-order nonlinear optical properties

Chemical Physics Letters, 2007

Research paper thumbnail of Underpotential deposition of hydrogen on benzene-modified Pt(111) in aqueous H2SO4

Langmuir : the ACS journal of surfaces and colloids, Jan 12, 2005

The Pt(111) electrode is modified by an overlayer of C6H6 (ads) upon its cycling in the 0.05-0.80... more The Pt(111) electrode is modified by an overlayer of C6H6 (ads) upon its cycling in the 0.05-0.80 V range in aq H2SO4 + 1 mM C6H6. The C6H6 (ads) overlayer significantly changes the underpotential-deposited H (H(UPD)) and anion adsorption, and cyclic-voltammetry (CV) profiles show a sharp cathodic peak and an asymmetric anodic one in the 0.05-0.80 V potential range. The C6H6 (ads) layer blocks the (bi)sulfate adsorption but facilitates the adsorption of one monolayer of H(UPD). Cycling of the benzene-modified Pt(111) in benzene-free aq 0.05 H2SO4 from 0.05 to 0.80 V results in a partial desorption of C6H6 (ads) and in a partial recovery of the CV profile characteristic of an unmodified Pt(111). The peak potential of the cathodic and anodic feature is independent of the scan rate, s (10 < or = s < or = 100 mV s(-1)), and the peak current density increases linearly with an increase of the scan rate. Temperature variation modifies the peak potential and current density but does n...

Research paper thumbnail of Multi-scale approach to the design of ferroelectric liquid crystals for NLO applications

Comparing data from ab initio calculations on a molecule and experimental measurements in the mat... more Comparing data from ab initio calculations on a molecule and experimental measurements in the material is not straightforward since environment and bulk symmetry have to be considered. To design compounds with performing properties, a multi-scale approach is proposed, combining molecular modeling with experimental and theoretical investigations. This procedure is applied to the design of new ferroelectric liquid crystals for NLO

Research paper thumbnail of Effect of Temperature Variation on the Under-Potential Deposition of Copper on Pt(111) in Aqueous H 2 SO 4

The Journal of Physical Chemistry C, 2009

Research paper thumbnail of Theoretical Design of the Molecular Structure of Bent-Core Mesogens with Large Second-Order Nonlinear Optical Properties

The Journal of Physical Chemistry C, 2012

Research paper thumbnail of Underpotential Deposition of Hydrogen on Benzene-Modified Pt(111) in Aqueous H 2 SO 4 †

Langmuir, 2005

The Pt(111) electrode is modified by an overlayer of C6H6 (ads) upon its cycling in the 0.05-0.80... more The Pt(111) electrode is modified by an overlayer of C6H6 (ads) upon its cycling in the 0.05-0.80 V range in aq H2SO4 + 1 mM C6H6. The C6H6 (ads) overlayer significantly changes the underpotential-deposited H (H(UPD)) and anion adsorption, and cyclic-voltammetry (CV) profiles show a sharp cathodic peak and an asymmetric anodic one in the 0.05-0.80 V potential range. The C6H6 (ads) layer blocks the (bi)sulfate adsorption but facilitates the adsorption of one monolayer of H(UPD). Cycling of the benzene-modified Pt(111) in benzene-free aq 0.05 H2SO4 from 0.05 to 0.80 V results in a partial desorption of C6H6 (ads) and in a partial recovery of the CV profile characteristic of an unmodified Pt(111). The peak potential of the cathodic and anodic feature is independent of the scan rate, s (10 &amp;amp;amp;amp;amp;amp;amp;amp;lt; or = s &amp;amp;amp;amp;amp;amp;amp;amp;lt; or = 100 mV s(-1)), and the peak current density increases linearly with an increase of the scan rate. Temperature variation modifies the peak potential and current density but does not affect the charge density of the cathodic or anodic feature. Temperature-dependent studies allow us to determine the thermodynamic state function for the H(UPD) adsorption and desorption. Delta G degrees(ads)(H(UPD))assumes values from -4 to -12 kJ mol(-1), while has values from 9 to 14 kJ mol(-1). The values of delta Delta G degrees (delta Delta G degrees = delat Delta G degrees(ads) + delta Delta D degrees(des)) decrease almost linearly from 6 kJ mol(-1) at theta(H(UPD) --&amp;amp;amp;amp;amp;amp;amp;amp;gt; 0 to 0 kJ mol(-1) at theta(H(UPD) --&amp;amp;amp;amp;amp;amp;amp;amp;gt; 1. The nonzero values of delta Delta G degrees testify that the adsorbing and desorbing H(UPD) adatoms interact with an energetically different substrate. The lateral interactions changed from repulsive (omega = 29 kJ mol(-1) at theta(H(UPD) --&amp;amp;amp;amp;amp;amp;amp;amp;gt; 0) to attractive (omega = -28 kJ mol(-1) at theta(H(UPD) --&amp;amp;amp;amp;amp;amp;amp;amp;gt; 1) as the H(UPD) coverage increases. The values of delta S degrees(ads)(H(UPD)) increase from 19 to 56 J K(-1) mol(-1), while those of delta S degrees(des)(H(UPD)) decrease from 45 to -30 J K(-1) mol(-1) with an increase of H(UPD) coverage. The values of delta H degrees(des)(H(UPD)) and delta H degrees(des)(H(UPD)) vary from 0 to 27 kJ mol(-1). The Pt(111)-H(UPD) surface bond energy at the benzene-modified Pt(111) electrode falls in the 191-218 kJ mol(-1) range and is weaker than in the case of the unmodified Pt(111) electrode in the same electrolyte.

Research paper thumbnail of Theoretical design of sulfinate-based ferroelectric liquid crystals displaying second-order nonlinear optical properties

Chemical Physics Letters, 2007

... Theoretical design of sulfinate-based ferroelectric liquid crystals displaying second-order n... more ... Theoretical design of sulfinate-based ferroelectric liquid crystals displaying second-order nonlinear optical properties. Frédéric Perreault a , Benoît Champagne b and Armand Soldera a , Corresponding Author Contact Information , E-mail The Corresponding Author. ...

Research paper thumbnail of Crystal structure of liquid-crystalline compounds possessing a 1,4-diaryl-1-buten-3-yne rigid core

... designed from an enyne (1,4-diaryl-1-buten-3-yne) rigid core inserted between alkoxy chains w... more ... designed from an enyne (1,4-diaryl-1-buten-3-yne) rigid core inserted between alkoxy chains was found to exhibit a rich thermal polymorphism; some compounds revealed up to four distinct mesophases [11. Soldera , A. , Beaudoin , M.-A. , O'Brian , G. , & Lessard , J. ( 2005 ). ...

Research paper thumbnail of Crystal structure of liquid-crystalline compounds possessing a 1,4-diaryl-1-buten-3-yne rigid core

... designed from an enyne (1,4-diaryl-1-buten-3-yne) rigid core inserted between alkoxy chains w... more ... designed from an enyne (1,4-diaryl-1-buten-3-yne) rigid core inserted between alkoxy chains was found to exhibit a rich thermal polymorphism; some compounds revealed up to four distinct mesophases [11. Soldera , A. , Beaudoin , M.-A. , O'Brian , G. , & Lessard , J. ( 2005 ). ...

Research paper thumbnail of Multi-scale approach to the design of ferroelectric liquid crystals for NLO applications

Comparing data from ab initio calculations on a molecule and experimental measurements in the mat... more Comparing data from ab initio calculations on a molecule and experimental measurements in the material is not straightforward since environment and bulk symmetry have to be considered. To design compounds with performing properties, a multi-scale approach is proposed, combining molecular modeling with experimental and theoretical investigations. This procedure is applied to the design of new ferroelectric liquid crystals for NLO

Research paper thumbnail of Theoretical Design of the Molecular Structure of Bent-Core Mesogens with Large Second-Order Nonlinear Optical Properties

The Journal of Physical Chemistry C, 2012

ABSTRACT The first hyperpolarizability of two series of mols. with bent-shaped structures has bee... more ABSTRACT The first hyperpolarizability of two series of mols. with bent-shaped structures has been calcd. at the ab initio level. The two series consist of carboxyl derivs. for which some mols. are known to exhibit banana phases and of their sulfinate homologues that have not been synthesized yet. The final purpose is to reveal the relevance or not in synthesizing these latter mols. The strategy is based on reporting the effect of the positions of donor and acceptor groups on the central benzene ring on the structural parameters and on the first hyperpolarizabilities. It is shown that in the sulfinate series the larger first hyperpolarizabilities are incompatible with efficient geometrical character while for the carboxyl series, the opening angle between the mol. arms is typical of banana-shaped mols. but the first hyperpolarizability is only slightly enhanced. Calcns. thus reveal that the sulfinate series does not need to be synthesized, whereas they show that our approach can be naturally applied to the development of new bent-shaped mols. for nonlinear optical applications. [on SciFinder(R)]

Research paper thumbnail of Theoretical design of sulfinate-based ferroelectric liquid crystals displaying second-order nonlinear optical properties

Chemical Physics Letters, 2007

Research paper thumbnail of Underpotential deposition of hydrogen on benzene-modified Pt(111) in aqueous H2SO4

Langmuir : the ACS journal of surfaces and colloids, Jan 12, 2005

The Pt(111) electrode is modified by an overlayer of C6H6 (ads) upon its cycling in the 0.05-0.80... more The Pt(111) electrode is modified by an overlayer of C6H6 (ads) upon its cycling in the 0.05-0.80 V range in aq H2SO4 + 1 mM C6H6. The C6H6 (ads) overlayer significantly changes the underpotential-deposited H (H(UPD)) and anion adsorption, and cyclic-voltammetry (CV) profiles show a sharp cathodic peak and an asymmetric anodic one in the 0.05-0.80 V potential range. The C6H6 (ads) layer blocks the (bi)sulfate adsorption but facilitates the adsorption of one monolayer of H(UPD). Cycling of the benzene-modified Pt(111) in benzene-free aq 0.05 H2SO4 from 0.05 to 0.80 V results in a partial desorption of C6H6 (ads) and in a partial recovery of the CV profile characteristic of an unmodified Pt(111). The peak potential of the cathodic and anodic feature is independent of the scan rate, s (10 < or = s < or = 100 mV s(-1)), and the peak current density increases linearly with an increase of the scan rate. Temperature variation modifies the peak potential and current density but does n...

Research paper thumbnail of Multi-scale approach to the design of ferroelectric liquid crystals for NLO applications

Comparing data from ab initio calculations on a molecule and experimental measurements in the mat... more Comparing data from ab initio calculations on a molecule and experimental measurements in the material is not straightforward since environment and bulk symmetry have to be considered. To design compounds with performing properties, a multi-scale approach is proposed, combining molecular modeling with experimental and theoretical investigations. This procedure is applied to the design of new ferroelectric liquid crystals for NLO

Research paper thumbnail of Effect of Temperature Variation on the Under-Potential Deposition of Copper on Pt(111) in Aqueous H 2 SO 4

The Journal of Physical Chemistry C, 2009

Research paper thumbnail of Theoretical Design of the Molecular Structure of Bent-Core Mesogens with Large Second-Order Nonlinear Optical Properties

The Journal of Physical Chemistry C, 2012

Research paper thumbnail of Underpotential Deposition of Hydrogen on Benzene-Modified Pt(111) in Aqueous H 2 SO 4 †

Langmuir, 2005

The Pt(111) electrode is modified by an overlayer of C6H6 (ads) upon its cycling in the 0.05-0.80... more The Pt(111) electrode is modified by an overlayer of C6H6 (ads) upon its cycling in the 0.05-0.80 V range in aq H2SO4 + 1 mM C6H6. The C6H6 (ads) overlayer significantly changes the underpotential-deposited H (H(UPD)) and anion adsorption, and cyclic-voltammetry (CV) profiles show a sharp cathodic peak and an asymmetric anodic one in the 0.05-0.80 V potential range. The C6H6 (ads) layer blocks the (bi)sulfate adsorption but facilitates the adsorption of one monolayer of H(UPD). Cycling of the benzene-modified Pt(111) in benzene-free aq 0.05 H2SO4 from 0.05 to 0.80 V results in a partial desorption of C6H6 (ads) and in a partial recovery of the CV profile characteristic of an unmodified Pt(111). The peak potential of the cathodic and anodic feature is independent of the scan rate, s (10 &amp;amp;amp;amp;amp;amp;amp;amp;lt; or = s &amp;amp;amp;amp;amp;amp;amp;amp;lt; or = 100 mV s(-1)), and the peak current density increases linearly with an increase of the scan rate. Temperature variation modifies the peak potential and current density but does not affect the charge density of the cathodic or anodic feature. Temperature-dependent studies allow us to determine the thermodynamic state function for the H(UPD) adsorption and desorption. Delta G degrees(ads)(H(UPD))assumes values from -4 to -12 kJ mol(-1), while has values from 9 to 14 kJ mol(-1). The values of delta Delta G degrees (delta Delta G degrees = delat Delta G degrees(ads) + delta Delta D degrees(des)) decrease almost linearly from 6 kJ mol(-1) at theta(H(UPD) --&amp;amp;amp;amp;amp;amp;amp;amp;gt; 0 to 0 kJ mol(-1) at theta(H(UPD) --&amp;amp;amp;amp;amp;amp;amp;amp;gt; 1. The nonzero values of delta Delta G degrees testify that the adsorbing and desorbing H(UPD) adatoms interact with an energetically different substrate. The lateral interactions changed from repulsive (omega = 29 kJ mol(-1) at theta(H(UPD) --&amp;amp;amp;amp;amp;amp;amp;amp;gt; 0) to attractive (omega = -28 kJ mol(-1) at theta(H(UPD) --&amp;amp;amp;amp;amp;amp;amp;amp;gt; 1) as the H(UPD) coverage increases. The values of delta S degrees(ads)(H(UPD)) increase from 19 to 56 J K(-1) mol(-1), while those of delta S degrees(des)(H(UPD)) decrease from 45 to -30 J K(-1) mol(-1) with an increase of H(UPD) coverage. The values of delta H degrees(des)(H(UPD)) and delta H degrees(des)(H(UPD)) vary from 0 to 27 kJ mol(-1). The Pt(111)-H(UPD) surface bond energy at the benzene-modified Pt(111) electrode falls in the 191-218 kJ mol(-1) range and is weaker than in the case of the unmodified Pt(111) electrode in the same electrolyte.

Research paper thumbnail of Theoretical design of sulfinate-based ferroelectric liquid crystals displaying second-order nonlinear optical properties

Chemical Physics Letters, 2007

... Theoretical design of sulfinate-based ferroelectric liquid crystals displaying second-order n... more ... Theoretical design of sulfinate-based ferroelectric liquid crystals displaying second-order nonlinear optical properties. Frédéric Perreault a , Benoît Champagne b and Armand Soldera a , Corresponding Author Contact Information , E-mail The Corresponding Author. ...

Research paper thumbnail of Crystal structure of liquid-crystalline compounds possessing a 1,4-diaryl-1-buten-3-yne rigid core

... designed from an enyne (1,4-diaryl-1-buten-3-yne) rigid core inserted between alkoxy chains w... more ... designed from an enyne (1,4-diaryl-1-buten-3-yne) rigid core inserted between alkoxy chains was found to exhibit a rich thermal polymorphism; some compounds revealed up to four distinct mesophases [11. Soldera , A. , Beaudoin , M.-A. , O'Brian , G. , & Lessard , J. ( 2005 ). ...