Novel Keggin-type polyoxometalate nanocatalysts for Michael addition polymerizations

Ahmadabad, Fatemeh Karimi; Pourayoubi, Mehrdad; Bakhshi, Hadi

doi:10.1016/j.matchemphys.2017.06.045

Cited by 9 publications

(9 citation statements)

References 49 publications

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“…The first step to mass loss in the regions of 100–200 °C with a maximum at 166 °C (20% weight loss) was due to the degradation of phosphor‐nitrogen fragments . The second step of mass loss in temperature regions of 200–360 °C with a maximum at 299 °C (39% weight loss) was related to the thermal degradation of aliphatic hydrocarbons within polymer backbone . The last mass loss at higher temperatures (360–500 °C) with a maximum at 392 °C (19%) was attributed to the degradation of the crosslinked structures generated during the second step .…”

Section: Resultsmentioning

confidence: 99%

“…The second step of mass loss in temperature regions of 200–360 °C with a maximum at 299 °C (39% weight loss) was related to the thermal degradation of aliphatic hydrocarbons within polymer backbone . The last mass loss at higher temperatures (360–500 °C) with a maximum at 392 °C (19%) was attributed to the degradation of the crosslinked structures generated during the second step . The high residue at 600 °C (22%) was expected since phosphorus‐containing polymers produce char on burning …”

Section: Resultsmentioning

confidence: 99%

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Chiral phosphoric triamide‐based polymers for enantioseparation

Ahmadabad

Pourayoubi

Bakhshi

2019

J of Applied Polymer Sci

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Novel optical isomers of phosphoramide-methacrylate monomers were synthesized and used for the preparation of corresponding polymers and hydrogels as chiral absorbents. In order to direct enantioseparation, two simple and inexpensive methods were designed: (a) immobilization of the chiral polymers on glass beads as packing material for the separation columns and (b) filling of chiral hydrogels in tea bags to fabricate separation bags. The specific rotations for R-and S-monomers were + 22.0 and − 21.8 , while those for R-and S-polymers were + 20.8 and − 22.1 , respectively. The enantioseparation of (AE)-α-methylbenzylamine, DL-alanine, DL-valine, DL-tartaric acid, DL-phenylalanine, and omeprazole was evaluated. The maximum enantioseparation (optical purity) of 97% was observed for (AE)-α-methylbenzylamine by S-hydrogel. Chiral hydrogels resulted in enantioseparations with higher purities (up to 97%) comparing to the chiral polymers, but in longer times (2-3 days). The desorption process easily occurred from the absorbed columns or bags.Phosphoramides with a P( O)(N) segment are attractive to study owing to their extensive applications in the coordination chemistry, catalysts, and medicine. [32][33][34] From our previous studies on phosphorus-oxygen, phosphorus-nitrogen, and phosphorus-sulfur compounds, 35-37 the P O group was found as the best hydrogen-bond acceptor with respect to the other possible acceptor groups, which usually exist in the molecules, typically C O, S O, N─O, P S, ester and ether oxygen atoms, nitrogen, and π-system, examined with X-ray diffraction study, statistical analysis based on the data deposited in the Cambridge structural database (CSD) 38 and quantum chemical calculations in some cases. The structures investigated include achiral, racemate, and chiral single-enantiomer phosphorus compounds. 36,37,39,40 According to Reaxys web-based tool (licensed by Elsevier) for chiral polymers, there is no report about an enantiomeric pair of phosphoric triamide-based polymers, and such polymers seem to be good chiral selectors, due to relatively strong interaction of P O with OH and NH units, as was observed in small molecules model compounds.In this work, levo-and dextro-rotatory isomers with two chiral centers, P( O)(NH-R-(−)CH(CH 3 )C 6 H 5 ) 2 (Cl) and P( O)(NH-S-(−)CH(CH 3 )C 6 H 5 ) 2 (Cl) (1 and 2), have been synthesized and reacted with 2-aminoethylmethacrylate (AEMA) to prepare phosphoric triamides monomers (3 and 4) as chiral selectors. The methacrylate moiety brought the opportunity for the radical or ionic polymerization reactions of these monomers. Through radical polymerization of these novel monomers, a pair of singleenantiomer phosphoric triamide-based polymers (P1 and P2) and hydrogels (H1 and H2) were prepared. In order to direct Additional Supporting Information may be found in the online version of this article.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Chiral phosphoric triamide‐based polymers for enantioseparation

Ahmadabad

Pourayoubi

Bakhshi

2019

J of Applied Polymer Sci

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“…Pourayoubi et al prepared the six keggin-type polyoxometalate nanoparticles based on [PW 12 O 40 ] 3- and [SiW 12 O 40 ] 4- with Ag + and (ZrO) 2+ cations under ultrasound irradiation, [181] and commandeered them to catalyze the synthesis of poly (amido-ester) at room temperature. The polyoxometalate nanoparticles could lead to the improvement by at least 22% in the polymerization yield, even though the molecular weight of polymers was decreased owing to the restrictive effect of heterogeneous nanocatalysts on the mobility of reactive groups at the end of growing polymer chains.…”

Section: Polymerizationmentioning

confidence: 99%

Sonochemical fabrication of inorganic nanoparticles for applications in catalysis

Zhuang

Dong

et al. 2021

Ultrasonics Sonochemistry

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“…This slight loss of activity may be due to a few changes in the morphology of nanoparticles in the presence of H 2 O/CH 3 OH/(AE)-MBA, which is usual for nano-compounds in the presence of chemicals, however, it was not further investigated. 53,80 A comparison of chiral adsorbents presented here with other chiral Fe 3 O 4 @SiO 2 -based adsorbents is given in Table 2. The Fe 3 O 4 @SiO 2 @PTA(+) and Fe 3 O 4 @SiO 2 @PTA(À) possess competitive advantages, such as high selectivity and recycling in the direct enantioseparation.…”

Section: Direct Separation Of Racemic Compoundsmentioning

confidence: 99%