Preparation and Characterization of N-4-Nitrophenyl-L-prolinol Nanocrystals in Sol–Gel Matrices

Sanz, Nathalie; Zaccaro, Julien; Delmotte, Luc; Luyer, Cécile Le; Ibanez, Alain

doi:10.1006/jssc.2001.9485

Cited by 12 publications

(10 citation statements)

References 22 publications

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“…In contrary to N-(4-nitrophenyl)-l-prolinol [15,16], the our compound of N-(4-nitrophenyl)-␤-alanine crystallizes in centrosymmetric space group therefore second harmonic generation should not be observed [17]. Nevertheless, the title compound seemed to be interested according to extensive and different N-H· · ·O, O-H· · ·O and N-H· · ·N hydrogen bonding system that has been characterized by X-ray crystallography and vibrational spectroscopy.…”

Section: Introductionmentioning

confidence: 94%

Crystal and molecular structure of N-(4-nitrophenyl)-β-alanine—Its vibrational spectra and theoretical calculations

Marchewka

Drozd

Janczak

2011

Spectrochimica Acta Part A: Molecular and Biomolecular Spectros

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Section: Introductionmentioning

confidence: 94%

Crystal and molecular structure of N-(4-nitrophenyl)-β-alanine—Its vibrational spectra and theoretical calculations

Marchewka

Drozd

Janczak

2011

Spectrochimica Acta Part A: Molecular and Biomolecular Spectros

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“…43 Indeed, we showed that the melting peak of NPP Ncs in the TMOS matrix is larger than that of the crystals in the TMOS/ MTMOS matrix. Moreover we demonstrated, by NMR measurements and Raman spectroscopy, 44 that there was a significant amount of non-aggregated NPP molecules which are grafted to silanol groups of the TMOS matrix. These strong dye-matrix interactions disturb dye aggregation.…”

Section: Nanocrystallization Principlesmentioning

confidence: 82%

Confined nucleation and growth of organic nanocrystals in sol–gel matrices

et al. 2006

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We have engineered new hybrid organic-inorganic materials through a simple and generic preparation of stable organic nanocrystals grown in gel-glass matrices. This process was based on confined nucleation and growth of dyes in the pores of dense gels. For bulk samples, narrow size distributions of particles were obtained between 10 and 20 nm in diameter. We extended this method to the preparation of organic nanocrystals embedded in sol-gel thin films by spin-coating. For all these nanocomposite samples, we significantly increased the dye stability and obtained promising optical properties (luminescence, NLO properties, SHG). Moreover we also demonstrated the basic working principles of a new type of fluorescent nanosensors through the preparation of organic luminescent nanocrystals grown in silicate films.

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“…In order to avoid the typical problem of cracks, due to capillary strengths, [18] the gels are slowly dried at room temperature for 4 to 6 weeks. [20] This extended period of time is unsuitable for high magnetic field experiments. Therefore we have optimized a new ORMO-SIL (organically modified silicate) matrix.…”

Section: Preparation and Orientation Of Organic Nanocrystalsmentioning

confidence: 99%

“…The melting point of randomly dispersed nanocrystals (NPP/GG) appears at higher temperatures This important thermal stabilization of NPP nanocrystals confined in the inorganic matrix is mainly due to hydrogen bonds existing between the nitro groups of NPP molecules located at the nanocrystal surfaces and the uncondensed silanol functions of the silicate network. [10,20] On the other hand, the melting point of NPP nanocrystals prepared under a high magnetic field appears at lower temperatures than that of randomly dispersed nanocrystals: mp(H/NPP/GG) = 160 C. Similar results were obtained for the POM: mp(POM) = 193 C, mp(POM/GG) = 248 C, and mp(H/POM/GG) = 243 C. This decrease of the melting temperature when the magnetic field is applied, associated with a narrower endothermic peak (DT = 5 C with H and DT = 6±7 C without, Fig. 1), could be explained by a decrease of the dye±matrix interactions through the magnetic field, leading to an increase of the crystallinity of the organic aggregates.…”

Section: Preparation and Orientation Of Organic Nanocrystalsmentioning

confidence: 99%

“…No specific polarization conditions were imposed during the collection of the different spectra. Spectra of a pure sol±gel matrix and a NPP powder measured under the same experimental conditions allowed the assignment of the spectral contributions of the gel glass and NPP nanocrystals, [20] respectively. Figure 2 shows the Raman spectra of NPP/GG and H/NPP/GG samples.…”

Section: Micro-raman and Luminescence Spectroscopies Of Npp Samplesmentioning

confidence: 99%

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Orientation of Organic Nanocrystals Grown in Sol–Gel Matrices under a High Magnetic Field

et al. 2002

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In order to obtain new optical properties, such as quadratic nonlinear optical or electro‐optical properties, we have undertaken the orientation control of organic nanocrystals during their growth in the pore of sol–gel matrices by applying a high magnetic field, H, of 16 T. H favors the dye aggregation and improves the crystalline quality of nanocrystals by reducing the orientation freedom of molecules and clusters through their diamagnetic susceptibility. When H is not applied, the NPP (N‐(4‐nitrophenyl)‐(L)‐prolinol) nanocrystals generate a weak second harmonic generation (SHG) intensity due to self‐oriented domains of nanocrystals induced by dipole–dipole interactions. In the case of 3‐methyl‐4‐nitropyridine‐1‐oxide (POM), which exhibits a very weak dipolar moment, no SHG signal can be detected. When H is applied, the SHG intensity of NPP nanocrystals increases significantly due to the reduction of their orientational freedom and the increase of dipole–dipole interactions, thus improving the formation of oriented domains of nanocrystals.

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Preparation and Characterization of N-4-Nitrophenyl-L-prolinol Nanocrystals in Sol–Gel Matrices

Cited by 12 publications

References 22 publications

Crystal and molecular structure of N-(4-nitrophenyl)-β-alanine—Its vibrational spectra and theoretical calculations

Crystal and molecular structure of N-(4-nitrophenyl)-β-alanine—Its vibrational spectra and theoretical calculations

Confined nucleation and growth of organic nanocrystals in sol–gel matrices

Orientation of Organic Nanocrystals Grown in Sol–Gel Matrices under a High Magnetic Field

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