An examination of chemically-modified silica surfaces using fluorescence spectroscopy

Lochmüller, C. H.; Marshall, David B.; Wilder, D. R.

doi:10.1016/s0003-2670(01)84148-9

Cited by 106 publications

(68 citation statements)

References 36 publications

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“…48) Dansyl amides experience a substantial bathochromic shift in fluorescence emission maximum with increasing solvent polarity making them useful in probing materials' microenvironments. 49), 50) Silica xerogel, prepared with a low concentration of dansyl 2 (0.001 mol %) to provide a measure of the polarity of the dry gel with minimal surface modification, had a dry fluorescence emission maximum of 515 nm. P-DA particles, with a thousand times more pendant dansyl 2, had a dry emission maximum of 476 nm indicating a more non-polar environment than the silica xerogel.…”

Section: Covalent Encapsulation Of 2 and 3 Viamentioning

confidence: 99%

Fluorescent hybrid organic–inorganic particles: influence of physical encapsulation versus covalent attachment on leaching and UV stability

Tolbert

Loy

2015

J. Ceram. Soc. Japan

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Hybrid organicinorganic materials provide the opportunity for combining organic chromophores into inorganic networks. The resulting hybrids can be used for numerous optical, biomedical and nanotechnology applications. Hybrid organicinorganic particles that absorb and fluoresce in visible or ultraviolet light are particularly useful for bio-imaging, sensors, and as a safe sunscreen. The organic component can be incorporated through physical entrapment or through covalent incorporation through siloxane linkages. By containment in the hybrid material, the performance lifetime of the chromophore can be extended significantly and environmental contamination by its leaching out can be reduced. In this study, silica particles containing 1 mol % dimethylaminonathyl-sulfonamide (dansyl) dyes were prepared by three different methods: 1) physical encapsulation inside a hollow silica particle, 2) covalent attachment of pendant chromophores through a single silyl group and 3) covalent attachment through two silyl groups. The influence of the mode of entrapment on the particles' spectroscopic properties, the propensity of the chromophores to leach from the particles, and photochemical degradation of chromophores were determined for the three classes of hybrid materials.

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Section: Covalent Encapsulation Of 2 and 3 Viamentioning

confidence: 99%

Fluorescent hybrid organic–inorganic particles: influence of physical encapsulation versus covalent attachment on leaching and UV stability

Tolbert

Loy

2015

J. Ceram. Soc. Japan

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“…The use of fluorescence to characterize silica surfaces is well-documented, especially for silica-based materials in chromatography. Specifically, fluorescence-based experiments on covalently attached [42][43][44][45][46][47][48][49][50][51][52][53][54] or physiosorbed probes [55][56][57][58][59][60][61][62][63] have been carried out to gain a better understanding of the accessibility, distribution, mobility, and orientation of surface-bound molecules (e.g., catalysts, ligands, reagents, and recognition elements).…”

Section: Introductionmentioning

confidence: 99%

Comparison of Dansylated Aminopropyl Controlled Pore Glass Solvated by Molecular and Ionic Liquids

et al. 2006

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We compare how (i) four ionic liquids (ILs) (1-butyl-3-methylimidazolium tetrafluoroborate ([C4mim][BF4]), 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C4mim][Tf2N]), 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide ([C4mpy][Tf2N]), and trihexyltetradecylphosphonium bis(trifluoromethylsulfonyl)imide ([P(C6)3C14][Tf2N])) and (ii) two conventional molecular liquids (methanol and 1-octanol) solvate/wet luminescent organic moieties that are covalently attached to the surface of silica controlled pore glass (CPG). A series of aminopropyl CPG particles that have been covalently tagged with the solvatochromic fluorescent probe group dansyl were used in this study. The results demonstrate that ILs solvate/wet the silica surface differently in comparison to molecular liquids (MLs). Specifically, when comparing ILs and MLs that appear to solvate the free probe, dansylpropylsulfonamide (DPSA), equally in solution, we find that ILs do not solvate/wet the silica surfaces as well as the corresponding MLs. The cation component in these ILs is the significant factor in how the ILs solvate/wet silica surfaces. Solvation/wetting of surface-bound species at a silica surface depends on the cation size. Chlorosilane end-capping of the surface silanol and amine residues attenuates the cation's affects.

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“…Both chromatographic and spectroscopic measurements show that the π s *, R s , and s values of bonded stationary phases are significantly greater than zero. [46][47][48][49][50][51][52][53] Typical values for π s * range from 0.7 to 1.1, between 0.8 and 1.1 for R s , and between 0.35 and 0.8 for s , depending on the mobilephase composition and type of organic solvent. 46, 52 All the above cited studies suggest that the stationary phase plays an important role in governing retention in RPLC.…”

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Comparative Study of Hydrocarbon, Fluorocarbon, and Aromatic Bonded RP-HPLC Stationary Phases by Linear Solvation Energy Relationships

et al. 1999

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The retention properties of eight alkyl, aromatic and fluorinated reversed-HPLC bonded phases were characterized through the use of Linear Solvation Energy Relationships (LSERs). The stationary phases were investigated in a series of methanol-water mobile phases. LSER results show that solute molecular size under all conditions and hydrogen bond acceptor basicity are the two dominant retention controlling factors and that these two factors are linearly correlated when either different stationary phases at a fixed mobile phase composition or different mobile phase compositions at a fixed stationary phase are considered.The large variation in the dependence of retention on solute molecular volume as only the stationary phase is changed indicate that the dispersive interactions between nonpolar solutes and the stationary phase are quite significant relative to the energy of the mobile phase cavity formation process.Principal Component Analysis (PCA) results indicate that one PCA factor is required to explain the data when stationary phases of the same chemical nature (alkyl, aromatic and fluoroalkyl phases) are individually considered. However, three PCA factors are not quite sufficient to explain the whole data set for the three classes of stationary phases. In spite of this, the average standard deviation obtained by the use of these principal components factors are significantly smaller than the average standard deviation obtained by the LSER approach. In addition, selectivities predicted through the LSER equation are not in complete agreement with experimental results.These results show that the LSER model does not properly account for all molecular interactions involved in RP-HPLC. The failure could reside in the V 2 solute parameter used to account for both dispersive and cohesive interactions since "shape selectivity" predictions for a pair of structural isomers are very bad.

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An examination of chemically-modified silica surfaces using fluorescence spectroscopy

Cited by 106 publications

References 36 publications

Fluorescent hybrid organic–inorganic particles: influence of physical encapsulation versus covalent attachment on leaching and UV stability

Fluorescent hybrid organic–inorganic particles: influence of physical encapsulation versus covalent attachment on leaching and UV stability

Comparison of Dansylated Aminopropyl Controlled Pore Glass Solvated by Molecular and Ionic Liquids

Comparative Study of Hydrocarbon, Fluorocarbon, and Aromatic Bonded RP-HPLC Stationary Phases by Linear Solvation Energy Relationships

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An examination of chemically-modified silica surfaces using fluorescence spectroscopy

Cited by 106 publications

References 36 publications

Fluorescent hybrid organic&ndash;inorganic particles: influence of physical encapsulation versus covalent attachment on leaching and UV stability

Fluorescent hybrid organic&ndash;inorganic particles: influence of physical encapsulation versus covalent attachment on leaching and UV stability

Comparison of Dansylated Aminopropyl Controlled Pore Glass Solvated by Molecular and Ionic Liquids

Comparative Study of Hydrocarbon, Fluorocarbon, and Aromatic Bonded RP-HPLC Stationary Phases by Linear Solvation Energy Relationships

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Fluorescent hybrid organic–inorganic particles: influence of physical encapsulation versus covalent attachment on leaching and UV stability

Fluorescent hybrid organic–inorganic particles: influence of physical encapsulation versus covalent attachment on leaching and UV stability