Cobalt porphyrin covalently bonded to organo modified silica xerogels

Quiroz-Segoviano, R.I.Y.; Rojas, Fernando; García-Sánchez, Miguel A.

doi:10.1016/j.jnoncrysol.2012.07.018

Cited by 13 publications

(23 citation statements)

References 49 publications

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“…As displayed in Fig. 5, the peak at À100 ppm was corresponding to the silicon atoms incorporated to the network through three siloxane unions and one remnant hydroxyl group, denoted as Q 3 ((Si-O-) 3 Si-OH); the peak at À110 ppm was ascribed to Q 4 ((Si-O-) 4 Si), in which the silicon is bonded to the walls of the pore network by means of four siloxane unions [24]. It was demonstrated that Q 3 occupied different ratios obtained from the peak area of Q 3 divided by the total peak areas of Q 3 and Q 4 in three composites.…”

Section: Resultsmentioning

confidence: 99%

The dependence of phase change enthalpy on the pore structure and interfacial groups in hydrated salts/silica composites via sol–gel

Wang

2015

Journal of Colloid and Interface Science

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Section: Resultsmentioning

confidence: 99%

The dependence of phase change enthalpy on the pore structure and interfacial groups in hydrated salts/silica composites via sol–gel

Wang

2015

Journal of Colloid and Interface Science

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“…On the other hand, substitution of Si-OH groups by alkyl or aryl groups, arising from organo-substituted silicon alkoxides (OSA), induces an even better display of luminescent properties of the fixed macrocycle. Additionally, the intensities of the UV-vis and fluorescence spectroscopic signals of the trapped macrocycle depend on the identity and size of the alkyl or aryl groups attached to the pore walls [39,40]. Through this combined trapping strategy, it has been possible to optimize the fluorescence of synthetic tetrapyrrolic species, as for instance the free bases of ortho- , meta- or para -substituted meso -tetraphenylporphyrins (H 2 T( o- , m- or p-S )PP) (Figure 1c), as well as the coordination and fluorescence of natural tetrapyrrolic species, such as chlorophyll a [41].…”

Section: Introductionmentioning

confidence: 99%

“…For this reason, the present document reports results about the physical entrapment or the covalent bonding of macrocyclic species inside non-siliceous (Ti and Zr) networks. The macrocyclic compounds employed herein were selected on the basis of their previous successful incorporation inside silica systems [32,34,35,36,37,38,39,40]. These compounds include MTSPc species and a cobalt tetra- para- carboxyphenylporphyrin (CoT( p- COOH)PP) compound.…”

Section: Introductionmentioning

confidence: 99%

Comparative Study of the Optical and Textural Properties of Tetrapyrrole Macrocycles Trapped Within ZrO2, TiO2, and SiO2 Translucent Xerogels

et al. 2015

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Abstract:The entrapping of physicochemical active molecules inside mesoporous networks is an appealing field of research due to the myriad of potential applications in optics, photocatalysis, chemical sensing, and medicine. One of the most important reasons for this success is the possibility of optimizing the properties that a free active species displays in solution but now trapped inside a solid substrate. Additionally it is possible to modulate the textural characteristics of substrates, such as pore size, specific surface area, polarity and chemical affinity of the surface, toward the physical or chemical adhesion of a variety of adsorbates. In the present document, two kinds of non-silicon metal alkoxides, Zr and Ti, are employed to prepare xerogels containing entrapped tetrapyrrolic species that could be inserted beforehand in analogue silica systems. The main goal is to develop efficient methods for trapping or binding tetrapyrrole macrocycles inside TiO2 and ZrO2 xerogels, while comparing the properties of these systems against those of the SiO2 analogues. Once the optimal synthesis conditions for obtaining translucent monolithic xerogels of ZrO2 and TiO2 networks were determined, it was confirmed that these substrates allowed the entrapment, in monomeric form, of macrocycles that commonly appear as aggregates within the SiO2 OPEN ACCESSMolecules 2015, 20 19464 network. From these experiments, it could be determined that the average pore diameters, specific surface areas, and water sorption capacities depicted by each one of these substrates, are a consequence of their own nature combined with the particular structure of the entrapped tetrapyrrole macrocycle. Furthermore, the establishment of covalent bonds between the intruding species and the pore walls leads to the obtainment of very similar pore sizes in the three different metal oxide (Ti, Zr, and Si) substrates as a consequence of the templating effect of the encapsulated species.

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“…The UV-Vis spectra of this sample ( Figure 17 a) revealed that the Co complex remained bonded and stable inside the silica pores. However, in these xerogels, the absorbance depicted by the respective UV-Vis spectra was proportional to the number of carbons present in the alkyl group attached to the pore surface [ 452 ]. Apparently, the alkyl chains remained close of the porphyrin molecule thus inhibiting the approach of interfering polar species.…”

Section: Tetrapyrrole Macrocycles and Cavity Pore Engineering Thromentioning

confidence: 99%

“… Where, MTSPc = Tetrasulfophthalocyanine, TPP = tetraphenylporphyrin, Ln = a lanthanide element, H 2 T(X or Y)PP = free bases of substituted tetraphenylporphyrins. Data from references [ 431 , 432 , 433 , 434 , 435 , 436 , 437 , 438 , 439 , 437 , 440 , 442 , 443 , 446 , 447 , 448 , 449 , 450 , 451 , 452 ]. …”

Section: Tetrapyrrole Macrocycles and Cavity Pore Engineering Thromentioning

confidence: 99%

Crossed and Linked Histories of Tetrapyrrolic Macrocycles and Their Use for Engineering Pores within Sol-Gel Matrices

et al. 2013

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The crossed and linked histories of tetrapyrrolic macrocycles, interwoven with new research discoveries, suggest that Nature has found in these structures a way to ensure the continuity of life. For diverse applications porphyrins or phthalocyanines must be trapped inside solid networks, but due to their nature, these compounds cannot be introduced by thermal diffusion; the sol-gel method makes possible this insertion through a soft chemical process. The methodologies for trapping or bonding macrocycles inside pristine or organo-modified silica or inside ZrO2 xerogels were developed by using phthalocyanines and porphyrins as molecular probes. The sizes of the pores formed depend on the structure, the cation nature, and the identities and positions of peripheral substituents of the macrocycle. The interactions of the macrocyclic molecule and surface Si-OH groups inhibit the efficient displaying of the macrocycle properties and to avoid this undesirable event, strategies such as situating the macrocycle far from the pore walls or to exchange the Si-OH species by alkyl or aryl groups have been proposed. Spectroscopic properties are better preserved when long unions are established between the macrocycle and the pore walls, or when oligomeric macrocyclic species are trapped inside each pore. When macrocycles are trapped inside organo-modified silica, their properties result similar to those displayed in solution and their intensities depend on the length of the alkyl chain attached to the matrix. These results support the prospect of tuning up the pore size, surface area, and polarity inside the pore cavities in order to prepare efficient catalytic, optical, sensoring, and medical systems. The most important feature is that research would confirm again that tetrapyrrolic macrocycles can help in the development of the authentic pore engineering in materials science.

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Cobalt porphyrin covalently bonded to organo modified silica xerogels

Cited by 13 publications

References 49 publications

The dependence of phase change enthalpy on the pore structure and interfacial groups in hydrated salts/silica composites via sol–gel

The dependence of phase change enthalpy on the pore structure and interfacial groups in hydrated salts/silica composites via sol–gel

Comparative Study of the Optical and Textural Properties of Tetrapyrrole Macrocycles Trapped Within ZrO2, TiO2, and SiO2 Translucent Xerogels

Crossed and Linked Histories of Tetrapyrrolic Macrocycles and Their Use for Engineering Pores within Sol-Gel Matrices

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