Publications by Julien Alexandre Andres

Sensitization Pathways in NIR-Emitting Yb(III) Complexes Bearing 0,+1,+2, or+3 Charges br

Yb(III) complexes of macrocyclic ligands based on 1,4,7,10-tetraazacyclododecane were synthesized. The ligands carried a carbostyril chromophore for Yb(III) sensitization, and carboxylate or carbamide donors for metal binding, forming complexes of 0, +1, + ...

2022

Colorimetry of Luminescent Lanthanide Complexes

Anne-Sophie Chauvin, Julien Alexandre Andres

Europium, terbium, dysprosium, and samarium are the main trivalent lanthanide ions emitting in the visible spectrum. In this work, the potential of these ions for colorimetric applications and colour reproduction was studied. The conversion of spectral dat ...

2020

Kinetics of the Regeneration by Iodide of Dye Sensitizers Adsorbed on Mesoporous Titania

Michael Graetzel, Jacques-Edouard Moser, Shaik Mohammed Zakeeruddin, Joël Teuscher, Julien Alexandre Andres, Arianna Marchioro, Peng Wang

Regeneration of dye sensitizer molecules by reducing species contained in the electrolyte is a key mechanism in liquid dye-sensitized solar cells because it competes kinetically with a detrimental charge recombination process. Kinetics of the reduction by ...

Amer Chemical Soc2014

Color Reproduction of Authenticable Luminescent Backlit Transmissive Color Images

Roger Hersch, Julien Alexandre Andres

We propose a method for creating authenticable color images under UV excitation backlight by printing an invisible luminescent white emissive ink layer on the verso side of a transmissive substrate and a classical cmy image on the recto side of the substra ...

Wiley-Blackwell2014

Synthesis of authenticable halftone images with non-luminescent halftones illuminated by an adjustable luminescent emissive layer

Roger Hersch, Julien Alexandre Andres

A method and computing system are proposed for producing an authenticable security device with two sides. The verso side is covered with an adjustable luminescent emissive layer formed by invisible luminescent ink halftones and possibly a UV absorbing prin ...

2014

A New Anti-Counterfeiting Feature Relying on Invisible Luminescent Full Color Images Printed with Lanthanide-Based Inks

Roger Hersch, Jacques-Edouard Moser, Anne-Sophie Chauvin, Julien Alexandre Andres

Europium and terbium trisdipicolinate complexes are inkjet printed onto paper with commercially available desktop inkjet printers. Together with a commercial blue luminescent ink, the red-emitting luminescent ink containing europium and the green-emitting ...

Wiley-Blackwell2014

Energy transfer in coumarin-sensitised lanthanide luminescence: investigation of the nature of the sensitiser and its distance to the lanthanide ion

Anne-Sophie Chauvin, Julien Alexandre Andres

A series of lanthanide complexes Ln(dpxCy)(3) have been synthesised. The ligands are composed of a coordinating dipicolinic acid backbone decorated with a polyoxyethylene arm fitted with a coumarin moiety at its extremity. The nature of the coumarin ...

Royal Society of Chemistry2013

Synthesis of authenticable halftone images with non-luminescent halftones illuminated by a luminescent emissive layer

Roger Hersch, Julien Alexandre Andres

A method and computing system are proposed for producing an authenticable security device with two sides. The verso side is covered with a luminescent emissive variable intensity layer formed for example by invisible luminescent ink halftones and the recto ...

2012

From Luminescent Lanthanide Complexes to Color Reproduction and Optical Document Security with Invisible Luminescent Inks

Julien Alexandre Andres

The present thesis deals with luminescent compounds based on lanthanide complexes that are suitable for color reproduction and optical document security with invisible luminescent inks. This thesis is divided in two distinct fields: chemistry, which produc ...

EPFL2012

6-Phosphoryl Picolinic Acids as Europium and Terbium Sensitizers

Anne-Sophie Chauvin, Julien Alexandre Andres

Three 6-phosphoryl picolinic acid (6PPA) derivatives were synthesized and used as europium and terbium sensitizers. Two of the three ligands (6-diethoxyphosphoryl picolinic acid (Hdeppa) and 6-monoethoxyphosphoryl picofinic acid (H(2)meppa)) are water-solu ...

2011

Europium Complexes of Tris(dipicolinato) Derivatives Coupled to Methylumbelliferone: A Double Sensitization

Anne-Sophie Chauvin, Julien Alexandre Andres

A para-poly(oxyethylene) dipicolinic acid derivative coupled to methylumbelliferone was synthesized and used as a ligand for coordination with europium ions. Characterization of the complex by mass spectrometry and spectrophotometry was performed in aqueou ...

Wiley-Blackwell2010

Catalytic Formal Homo-Nazarov Cyclization

Julien Alexandre Andres, Jérôme Waser, Filippo De Simone, Riccardo Torosantucci

The first catalytic method for the cyclization of vinyl-cyclopropyl ketones (formal homo-Nazarov reaction) is reported. Starting from activated cyclopropanes, heterocyclic and carbocyclic compounds were obtained under mild conditions using Brønsted acid ca ...

American Chemical Society2009