Alginic acids and alginates: analytical methods used for their estimation and characterisation of composition and primary structure

Усов, А. И.

doi:10.1070/rc1999v068n11abeh000532

Cited by 69 publications

(25 citation statements)

References 179 publications

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“…The biomolecule used, alginic acid, is a straight-chain polyuronic acid, made up of b-D-mannuronic and a-L-guluronic acid residues (in the pyranose form) linked by 1 ® 4 bonds. [27,28] Figure 1 shows the conformations of the monosaccharide units in alginic acid. The pKa values for mannuronic and guluronic acid are 3.38 and 3.65, respectively.…”

Section: Methodsmentioning

confidence: 99%

“…Based on numerous studies including methylation, periodate oxidation, and several physicochemical methods of structural analysis, the repeat units of alginic acid are deduced to be linear and made up of b-D-mannuronic and a-L-guluronic acid residues linked via 1 ® 4 bonds. [27,28] Previous research suggested that these linear molecules could react with inorganic ions to form chain-shaped intermediates, [28,30] which might serve as a template for the synthesis of 1D nanomaterials. In the case of the synthesis of tellurium nanowires, a large number of hydroxyl (±OH) groups on the surface of alginic acid could react with TeO 2± 4 groups to form chain-shaped intermediates, which could decompose to form tellurium crystals upon reduction.…”

Section: Methodsmentioning

confidence: 99%

“…The pKa values for mannuronic and guluronic acid are 3.38 and 3.65, respectively. [28] Alginic acid is extracted from macrocystis pyrifera (kelp) and has been extensively used in pharmacy and cosmetic materials. Recently, it has been used as a biosorption agent for heavy metals and to make iron-oxide nanomaterials.…”

Section: Methodsmentioning

confidence: 99%

“…Recently, we reported that three-dimensional colloidal crystals could be intentionally utilized to fabricate two-dimensional mesoscopic arrays and self-assembled monolayers via the ªcolloidal-crystal-assisted capillary nanofabricationº (CCACN) method. [28] However, there are limitations for patterning hybrid multilayered structures and fabricating hierarchical patterns using CCACN, ªmicromolding in capillariesº (MIMIC), [29] ªmicrofluidic networkº (lFN), [30,31] micro/nanosphere lithography, [2,17,32,33] and controllable wetting approaches.…”

Section: Methodsmentioning

confidence: 99%

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Biomolecule‐Assisted Reduction in the Synthesis of Single‐Crystalline Tellurium Nanowires

Gao

Komarneni³

2004

Advanced Materials

131

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are both localized on the substituted side fluorene groups), a sizeable increase in electron affinity (by~0.91 eV) is achieved in poly-S-m-Br-methoxy in comparison to S-methoxy. Such donor±acceptor molecular systems might not be appropriate for blue-light emission: the triplet energy is indeed bounded upwards by that of the substituted units, which itself relates to the donor/acceptor strengths (hence only weak electroactive groups, translating into small changes in HOMO±LUMO energies, will ensure high singlet±triplet energy separations); however, they yield the smallest bandgap among all investigated hosts for green-light emission.To summarize, we have performed DFT calculations in order to design molecular hosts suitable for efficient colortunable triplet emission. Focusing on the carbazole and spiro building blocks, the influence of molecular topology on the triplet excited-state properties has been explored.The DFT results indicate the following:d host materials suitable for blue-light-emitting devices can be designed by interconnecting CBZ and spiro monomers through their meta (3,6) positions. In this case, the triplet wavefunction is mostly localized over 2 phenyl rings and the calculated S 0 ±T 1 energy gap amounts to~3 eV.d sequential interconnection in para (2,7) and meta positions causes the triplet to be more delocalized (typically over 3 phenyl rings), which considerably lowers the triplet energy. This route can be used to prepare hosts that are suitable for green-light-emitting devices.d interconnecting monomers in para positions leads to the triplet being delocalized over~4 phenyl rings and further lowers the singlet-triplet energy gap. Such compounds, which are characterized by the lowest ionization potentials and highest electron affinities, are the best candidates to be used as hosts in red-light-emitting devices. To further improve charge injection while maintaining a constant singlet±triplet gap, a series of oligomers substituted with electroactive groups on the side fluorene moieties of their spiro units have been investigated. This approach was found to be successful in the case of molecular architecture involving para connections between the spiro units, as in these molecules the triplet is confined to the main backbone while the HOMO and LUMO are localized on the side fluorenes. In contrast, the lowest triplet state of the oligomers with interconnections in meta positions is localized on the side segments, because in this case the energy gain caused by the substitution overwhelms that due to the interactions along the backbone. Therefore, the highest triplet energy that can be achieved in such configuration is bounded by the S 0 ±T 1 energy difference in the isolated substituted chromophore. For both para and meta inter-connected oligomers, the proposed strategy enables the dramatic improvement of hole and electron injection in hosts for green-and red-light emission. ExperimentalComputational Details: Density functional theory (DFT) [10] calculations were performed using the B3LYP hybrid f...

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

See 2 more Smart Citations

Biomolecule‐Assisted Reduction in the Synthesis of Single‐Crystalline Tellurium Nanowires

Gao

Komarneni³

2004

Advanced Materials

131

View full text Add to dashboard Cite

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“…Although a series of chromatographic methods have been developed for the analysis of alginic acid, the focus has been on structural studies [8]. In other words, high performance liquid or gas chromatography has been applied after reproducible chemical or enzymatic fragmentation, with detection emphasising chemical derivatisation to enhance the response for absorption or fluorescence spectroscopy.…”

Section: Introductionmentioning

confidence: 99%