Fluorometric Studies of Pyrene Adsorption on Porous Crystalline Cellulose

Tozuka, Yuichi; Yonemochi, Etsuo; Oguchi, Tamio; Yamamoto, Keiji

doi:10.1006/jcis.1998.5722

Cited by 23 publications

(14 citation statements)

References 18 publications

(17 reference statements)

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“…Finally, we will show by LSE relationships as reported in the literature that other spectroscopic results of recent papers [4][5][6] correlate well with our results of solvatochromism of polarity indicators for cellulose samples.…”

Section: Introductionsupporting

confidence: 58%

“…As seen from Eq. (6) m max,4 N 10 -3 [cm -1 ] = 28.54 + 1.302 a (6) where n = 7; r = 0.97; sd = 0.34 in HBD solvents, the influence of the a value upon m max,4 is hypsochromic, indicating a stronger specific interaction of the active hydrogen atoms of the solvents with the lone pair of the amino group rather than with those of the carbonyl oxygen.…”

Section: Probe Dye Indicators and Determination Of The Polarity Parammentioning

confidence: 99%

“…[3] In the past time period from 1997 till now, several other papers appeared dealing with similar topics: the acid, base and polarity properties of native cellulose. Inverse gas chromatography, [4] FTIR spectroscopy [5] and fluorescence measurements [6][7][8] have been used to treat the problem. However, despite many papers reporting on polarity properties of polysaccharides, relevant values of empirical polarity parameters are still not established.…”

Section: Introductionmentioning

confidence: 99%

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Empirical surface polarity parameters for native polysaccharides

Fischer

Spange²

2000

Macromol. Chem. Phys.

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The empirical Kamlet‐Taft solvatochromic polarity parameters α, β, and π* as well as calculated Reichardt's ET(30) values are presented for microcristalline cellulose, cellobiose, chitine, amylose, amylopectine, and glycogene. For this purpose, the following solvatochromic polarity indicators were applied: 2,6‐diphenyl‐4‐(2,4,6‐triphenyl‐1‐pyridinio)phenolate (1), [4,4′‐bis(N,N‐dimethylamino)benzophenone] (2), dicyano‐bis(1,10‐phenanthroline) iron(II) [Fe(phen)2](CN)2 (3), and 4‐aminobenzophenone (4). The polarity of the microcristalline environment of cellulose can be exactly parameterized in terms of the Kamlet‐Taft α, β, and π* values. The analogy of these values to those of the model compound cellobiose and of other independent literature data, i.e. calculated π* values via LSE (Linear Solvation Energy) relationships derived from FTIR and fluorescence measurements, is excellent. Microcristalline cellulose exhibit strong HBD properties and a rather low value of the dipolarity/polarizability. The substitution of the hydroxy group in the 2 position of the anhydroglucose unit of cellulose with the polarizable acetamido group (cellulose → chitine) significantly enhances the dipolarity/polarizability of the polysaccharide whereas the HBD capacity accordingly decreases. A generalized empirical polarity scale for native polysaccharides is suggested.

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Section: Introductionsupporting

confidence: 58%

Section: Probe Dye Indicators and Determination Of The Polarity Parammentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Empirical surface polarity parameters for native polysaccharides

Fischer

Spange²

2000

Macromol. Chem. Phys.

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“…Crystalline organic materials change to an amorphous state when they are stored with porous materials through gaseous adsorption of molecules onto the surface (1,2). The amorphous form of drug molecules exhibited a greater dissolution rate and greater bioavailability than the crystalline form (3)(4)(5).…”

Section: Introductionmentioning

confidence: 99%

Solid-State Fluorescence Study of Naphthalene Adsorption on Porous Material

Tozuka

Tashiro

Yonemochi

et al. 2002

Journal of Colloid and Interface Science

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“…7,8) Porous materials have a unique capacity to adsorb organic compounds due to their large specific surface area and porous structure. Activated carbon, porous crystalline cellulose, and zeolites are examples of porous materials that have been used widely for pharmaceuticals.…”

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confidence: 99%

Effect of Pore Size of FSM-16 on the Entrapment of Flurbiprofen in Mesoporous Structures

et al. 2005

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The improvement of bioavailability of poorly water-soluble drugs is important for oral administration. Amorphization is one of the techniques that has been commonly used for solubility enhancement.1,2) Amorphous material of drug can be obtained by several methods, e.g., spray-drying, 3) solid dispersion, 4) co-grinding with cyclodextrins 5) or crystalline cellulose, 6) and mixing with porous materials. 7,8) Porous materials have a unique capacity to adsorb organic compounds due to their large specific surface area and porous structure. Activated carbon, porous crystalline cellulose, and zeolites are examples of porous materials that have been used widely for pharmaceuticals. [9][10][11] Folded sheets mesoporous material (FSM-16) has been synthesized by an intercalation of quaternary ammonium surfactant as a template in a layered polysilicate kanemite, followed by calcination.12-16) FSM-16 is composed of hexagonal channels and has extremely large specific surface area and large pore volume. Due to its highly uniform porous structure with hexagonal arrays, FSM-16 is widely used as a reactor for catalytic reaction, as an adsorbent and as a host for the inclusion of large molecules. 17,18) Itoh et al. 19) studied the photostability of chlorophyll a after adsorption into FSM-16. The enhancement of the photostability was attributable to the interactions between chlorophyll and FSM-16 to form chlorophyll-FSM conjugate, and also between two chlorophyll molecules to form a chlorophyll dimer within the pores of FSM-16.In the previous paper, we investigated the use of FSM-16 for pharmaceutical applications. We reported the change in molecular state of salicylamide from crystal to amorphous by adsorption into the FSM-16 channels during sealed-heating process. The amorphization of the drug accordingly resulted in enhanced dissolution of sealed-heated sample. 20) In the present study, three kinds of FSM-16 with different pore diameters [FSM-16(Oc), FSM-16(Do) and FSM-16(Doc)] were employed to investigate the molecular state of the drug and its interaction with FSM-16. Flurbiprofen (FBP), a poorly water-soluble non-steroidal anti-inflammatory drug, was used as a model compound. Changes in the molecular state of FBP were investigated using powder X-ray diffractometry, thermal analysis and FT-IR spectroscopy. The changes in pore diameter and specific surface area of samples prepared by various methods were investigated using small angle X-ray scattering and nitrogen gas adsorption BET method for understanding the effect of adsorption of FBP molecules on pore structure of FSM-16. ExperimentalMaterials Flurbiporfen (FBP) of reagent grade was kindly supplied by Kaken Pharmaceutical, Co. Ltd., Japan, and was used without further purification. Three kinds of mesoporous silica FSM-16, i.e., FSM-16(Oc), FSM-16(Do) and FSM-16(Doc), were kindly supplied by Toyota Central R&D Labs., Inc., Japan. Mean pore width and specific surface area of FSM-16(Oc), FSM-16(Do), FSM-16(Doc) were 16.0, 21.6, 45.0 Å and 700, 1250, 1040 m 2 /g, respectively...

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Fluorometric Studies of Pyrene Adsorption on Porous Crystalline Cellulose

Cited by 23 publications

References 18 publications

Empirical surface polarity parameters for native polysaccharides

Empirical surface polarity parameters for native polysaccharides

Solid-State Fluorescence Study of Naphthalene Adsorption on Porous Material

Effect of Pore Size of FSM-16 on the Entrapment of Flurbiprofen in Mesoporous Structures

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