Spectroscopy of BODIPY in solid phase: crystal and nanoparticles

• Published in: PCCP. Physical chemistry chemical physics (Print) Vol. 15; no. 9; pp. 3186 - 3195
• Main Authors: YUANYUAN LIAO, GENOT, Valérie, MEALLET-RENAULT, Rachel, VU, Thanh T, AUDIBERT, Jean-Frédéric, LEMAISTRE, Jean-Pierre, CLAVIER, Gilles, RETAILLEAU, Pascal, PANSU, Robert B
• Format: Conference Proceeding Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 07.03.2013
• Subjects: Absorption; Absorption spectra; Boron Compounds - chemistry; Chemistry; Colloidal state and disperse state; Crystallography, X-Ray; Crystals; Exact sciences and technology; Excitation; Fluorescence; Fluorescent Dyes - chemistry; General and physical chemistry; Mathematical models; Models, Molecular; Molecular Conformation; Nanoparticles; Nanoparticles - chemistry; Particle Size; Physical and chemical studies. Granulometry. Electrokinetic phenomena; Single crystals; Spectra; Spectrometry, Fluorescence; Dyes; Nanoparticle; Theory; Prediction; Fluorescence; Hydrodynamics; Suspension; Crystallography; Monoclinic crystals; Wavelength; Single crystal; Absorption spectrum; Absorption; Focusing; Dichroism; Density functional method; Birefringence; Dimer; Models; Solid phase; Room temperature
• ISSN: 1463-9076; 1463-9084
• DOI: 10.1039/c2cp43289g

We compare the absorption and fluorescence spectra of single crystals and suspensions of nanoparticles with the prediction of the Frenkel theory. The single crystals of a novel synthesized fluorescent BODIPY derivative dye, adamantyl mesityl BODIPY (4,4-difluoro-3,5-di-(adamantyl)-8-mesityl-4-bora-3a,4a-diaza-s-indacene), have been prepared. Their birefringence and dichroism have been studied. The X-ray crystallography shows a monoclinic crystal with all transition moments parallel to one common plane. The refractive indices along the two neutral axes have been measured for a wavelength from 530 to 700 nm, with a difference, Δn equal to 0.11. The Frenkel exciton theory was used here to describe the coupling of the electronic excited states in the crystals. The coupling estimated by the dipolar approximation was compared with the excited state splitting calculated by TDDFT in dimers. A perfect crystal absorption spectrum is predicted. The spectral broadening that occurs at room temperature is also taken into account. The absorption spectrum of the monocrystal is reproduced without adjustable parameters. But we had to take into account the presence of optical leaks in our microspectrophotometer before comparing experiment and theory. The controlled size nanoparticles (NPs) produced by our 3D hydrodynamic focusing microfluidic system exhibit molecule like absorption. We could reproduce their absorption and fluorescence spectra assuming a strong disorder in the Frenkel model. We conclude that the nanoparticles are amorphous.