Browsing by Author "Sobarzo, Patricio A."

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    Comparison between poly(azomethine)s and poly(p-phenylvinylene)s containing a di-R-diphenylsilane (R = methyl or phenyl) moiety. Optical, electronic and thermal properties
    (2021) Sobarzo, Patricio A.; Mariman, Andrea P.; Sanchez, Christian O.; Hauyon, Rene A.; Rodriguez-Gonzalez, Fidel E.; Medina, Jean; Jessop, Ignacio A.; Recabarren-Gajardo, Gonzalo; Tundidor-Camba, Alain; Terraza, Claudio A.
    Two new silicon-containing poly(azomethine)s (PAzM-Me and PAzM-Ph) and two new silicon-containing poly(pphenylvinylene)s (PPVSi-Me and PPVSi-Ph) were obtained from 4',4'''-(dimethylsilanediyl)bis([1,1 '-biphenyl]-4-carbaldehyde) and 4',4'''-(diphenyl silanediyl)bis([1,1 '-biphenyl]-4-carbaldehyde) with p-phenylendiamine for PAzMs or phenylenebis(methylene))bis(triphenylphosphonium) bromide for PPVSis. All polymers were structurally characterized by FT-IR, NMR and elemental analysis. The materials showed a high thermal stability (501-538 degrees C) with the TPS-core increasing this parameter. The absorption and emission of PAzMs and PPVSis were closely related with the nature of the silane-core in the backbone. All samples showed wide-band gaps where the TPS-core-based materials evidenced the lower energy transitions; PAzM-Ph (2.83 eV) and PPVSi-Ph (2.81 eV). This work lay the groundwork for new architectures of silane-based poly(azomethine)s and poly(p- phenylvinylene)s derivatives for potential optoelectronic applications.
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    Effect of thiophene, furan moieties and zinc ions on melamine-based porous polyaminals properties and catalytic activity on CO2 cycloaddition reaction
    (2022) Sobarzo, Patricio A.; Tundidor, Alain; Sanz-Perez, Eloy S.; Terraza, Claudio A.; Maya, Eva M.
    A new series of melamine-based porous polyaminals containing thiophene or furan moieties of different size in the polymer network were prepared and fully characterized. The new polyaminals were N-rich polymers with nitrogen content between 10 and 28%, exhibited micro-, meso- or macroporosity, depending on the type and size of the thiophene or furan moiety with specific surface areas in the range of 23-490 m(2)/g. The CO2 uptakes were moderated, between 1 and 5% and those polyaminals with higher CO2 uptake capacity were selected as catalysts to promote the conversion of CO2 into cyclic carbonate and also to prepare the corresponding zinc complexes, which were used as catalysts in the same reaction. The selected catalysts showed good catalytic performance working under much milder reaction conditions (CO2 pressure of 4 bar, 80 degrees C, 0.1 mol % of cocatalyst) than the examples of melamine-based polyaminals published so far for this reaction.
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    Microwave-assisted melamine-based polyaminals and their application for metal cations adsorption
    (2021) Sandin, Ricardo; Gonzalez-Lucas, Maria; Sobarzo, Patricio A.; Terraza, Claudio A.; Maya, Eva M.
    Three new cross-linked melamine-based polyaminal networks containing phenyl (MA-iPh), pyridine (MA-Py) or thiophene (MA-Th) moieties were easily prepared by microwave irradiation (MW) in shorter reaction times (between 1.5 and 4 h) than conventional heating (72 h). The networks showed high nitrogen content (27-37%), specific surfaces between 34 and 424 m(2)g(-1) and high thermal stability (300 degrees C). The adsorption capacity of these polyaminals was determined over different toxic metals such as Cr(VI), Cu(II), Cd (II) and Pb(II) at different pH. The results showed greater chromium adsorption capacity in acid medium (pH 2), while the divalent cations were mainly adsorbed at pH 5. MA-Py that displayed the highest nitrogen content (37%) and highest specific surface area (424 m(2)g(-1)) also showed the highest adsorption capacities of this series, with values of 27.22, 26.42, and 53.13 mg/g for Cr(VI), Cd(II) and Pb(II); respectively. Additionally, MA-Py and MA-iPh with adsorption capacities of 29.12 and 25.02 mgg 1 for Cr(VI) and Cd(II), were competitive in terms of adsorption capacities regarding commercial ion exchange-resins which shown adsorptions in the range 13.7-21.3 mg/g.
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    Synthesis of dimethyl- and diphenylsilane-based oligo(azine)s: Thermal, optical, electronic, and morphological properties
    (2022) Sobarzo, Patricio A.; Jessop, Ignacio A.; Perez, Yasmin; Hauyon, Rene A.; Velazquez-Tundidor, Maria V.; Medina, Jean; Gonzalez, Alexis; Garcia, Luis E.; Gonzalez-Henriquez, Carmen M.; Coll, Deysma; Ortiz, Pablo A.; Tundidor-Camba, Alain; Terraza, Claudio A.
    Four new oligo(azine)s were synthesized from dimethyldiphenylsilane and tetraphenylsilane core-based dialdehydes and hydrazine by high-temperature polycondesation and proposed as materials for optoelectronic applications. The oligo(azine)s were characterized by EA, FT-IR, and NMR. Although most of samples were poorly soluble, TPS-containing PAZ-4 was soluble in aprotic polar solvents. According to SEC and FT-IR studies, the samples were oligomers with up to five repeating units long. TGA showed highly stable samples with TDT10% over 420 degrees C except for PAZ-1 that contains a DMS core along with phenyl units, and thus, the lowest carbon content in the series. From DSC analysis, the substitution of phenyl groups in PAZ-1/3 by biphenyl moieties in PAZ-2/4 allowed to obtain oligo(azine)s with lower T-g values. PAZ-4 showed a UV-A absorption with optical band-gap values of 2.91 and 2.65 eV from UV-vis (solution) and DRS (films), respectively. PL analysis showed a violet emission. PAZ-4 showed resistivity of 29.24 omega cm, similar to wide-band gap materials. Their contact angle measurements showed a critical surface tension of 42.29 dynes/cm, revealing its hydrophobicity. AFM analysis indicated that the PAZ-4 films had homogeneous surfaces. Young's modulus close to 4.46 GPa was established by microindentation for the PAZ-4 thin-films.
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    Tetraphenylsilane-based oligo(azomethine)s containing 3,4-ethylenedioxy- thiophene units along their backbone: Optical, electronic, thermal properties and computational simulations
    (2022) Sobarzo, Patricio A.; Gonzalez, Alexis; Jessop, Ignacio A.; Hauyon, Rene A.; Medina, Jean; Garcia, Luis E.; Zarate, Ximena; Gonzalez-Henriquez, Carmen; Schott, Eduardo; Tundidor-Camba, Alain; Terraza, Claudio A.
    A series of three new oligo-poly(azomethine)s (o-PAzMs) were successfully synthesized, incorporating tetra-phenylsilane (TPS) and 3,4-ethylenedioxythiophene (EDOT) moieties with Mn and Mw between 3.9 and 5.4 kDa and 8.3-11.6 kDa, respectively. The silylated o-PAzMs were highly soluble in low-boiling point solvents such as CHCl3, THF, and CH2Cl2. All three materials are highly thermally stable, with onset temperatures of degradation of at least 250 degrees C and with TDT10% between 340 and 460 degrees C. The glass transition temperature values agree with the flexibility of the repetitive units and showed values between 125 and 155 degrees C. The absorption and emission of the o-PAzMs were observed in the blue-violet UV-vis region (350-550 nm) with moderate Stokes shifts (48-71 nm). The oligomers are it-conjugated wide-band gap materials (2.83-2.73 eV), where the high electronic tran-sitions would be associated with disruption of it-conjugation, which is promoted by the TPS core and (d-p)it orbital interactions. This disruption controls the effect from the EDOT unit rich donor on HOMO (-5.79 eV to-5.71 eV) and LUMO (-2.98 eV to-2.89 eV) energy values. Furthermore, DFT and TDDFT calculations were performed to theoretically characterize the observed UV-Vis transitions and frontier molecular orbitals (MOs) energies.
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    Thiophene- and bithiophene-based π-conjugated Schiff base oligomers containing binaphthalene moieties in the backbone. Properties and computational simulations
    (2024) Gonzalez, Alexis F.; Mariman, Andrea P.; Hauyon, Rene A.; Pavez-Lizana, Danitza; Saldias, Cesar; Schott, Eduardo; Zarate, Ximena; Garcia, Luis; Gonzalez-Henriquez, Carmen M.; Jessop, Ignacio A.; Tundidor-Camba, Alain; Sobarzo, Patricio A.; Terraza, Claudio A.
    New pi-conjugated Schiff base oligomers (o-AZdAN1Th and o-AZdAN2Th) based on a binaphthalene core and containing thiophene or bithiophene units in their backbone were synthesized from the reaction between [1,1 '-binaphthalene]-4,4 '-diamine with thiophene-2,5-dicarbaldehyde and [2,2 '-bithiophene]-5,5 '-dicarbaldehyde by a high-temperature polycondensation method. These new materials were slightly soluble in non-protic polar solvents, such as chloroform and dichloromethane. From GPC analysis of the CHCl3-soluble fraction, o-AZdAN1Th was found to be a tetramer, whereas o-AZdAN2Th was a trimer with 1.4 kDa and 1.3 kDa average molecular weight (Mn), respectively. Both samples exhibited high thermal stability with T5% values of 452 degrees C and 456 degrees C and relatively high Tg values of 346 degrees C and 384 degrees C, for o-AZdAN1Th and o-AZdAN2Th, respectively. The samples showed absorptions in the deep-blue (o-AZdAN1Th) and blue (o-AZdAN2Th) regions of the visible spectrum, and emission responses at 387 nm and 447 nm, respectively, with moderate Stokes shifts (77-95 nm). Their optical and electronic properties were similar to those described for thiophene-based materials, with optical bandgap values close to 2.4 eV. HOMO energy values of -5.98 and -5.95 eV and LUMO energy values of -3.87 eV and -3.84 eV were obtained for o-AZdAN1Th and o-AZdAN2Th, respectively. Theoretical DFT and TD-DFT calculations were used to compare the effect of increasing thiophene units along the backbone for the real and also theoretical o-AZdANxTh samples (x = 3 and 4 thiophene units). According to our study, these two new thiophene-based can be proposed for optoelectronic applications.