scholarly journals Effect of Side Groups on the Hydrolytic Stability of Thiolated and Disulfide Cross-linked Polyaspartamides

2021 ◽  
Vol 65 (2) ◽  
pp. 183-191
Author(s):  
Benjámin Gyarmati ◽  
Aysel Mammadova ◽  
Gergely Stankovits ◽  
Dóra Barczikai ◽  
András Szilágyi
Keyword(s):  
Nmr Spectroscopy ◽  
1H Nmr Spectroscopy ◽  
Chemical Structure ◽  
Main Chain ◽  
Hydrolytic Stability ◽  
Linear Polymers ◽  
Dynamic Moduli ◽  
Oscillatory Rheology ◽  
Thiol Content ◽  
Biomedical Fields

Thiolated polyaspartamides either with N,N-dimethyl-2-aminoethyl (DME), N,N-dimethyl-3-aminopropyl (DMP) or 2-hydroxyethyl (HE) side groups were synthesized to study the effect of side groups on the hydrolytic stability of these polymers. The chemical structure of linear polymers was confirmed by 1H NMR spectroscopy, while thiol content was determined by Ellman's assay. Hydrolytic stability of thiolated polyaspartamides was studied by viscosity measurements and results suggested main-chain degradation in the presence of DME side groups. Polyaspartamides with DMP or HE side groups showed considerable stability. Thiolated polyaspartamides were converted to their disulfide cross-linked hydrogels and the gelation process was followed by oscillatory rheology. Time-dependence of dynamic moduli indicated the degradation of hydrogels containing DME side groups, while stable moduli were observed for hydrogels containing DMP or HE side groups. This structure-dependent aqueous degradation of polyaspartamides can be useful in different biomedical fields.

scholarly journals Synthesis of new 3-(2-aminothiazol-4-yl)-4-hydroxy-2H-chromen-2-one derivatives

2006 ◽  
Vol 71 (6) ◽  
pp. 581-585 ◽  
Author(s):  
S. Sukdolak ◽  
N. Vukovic ◽  
S. Solujic ◽  
M. Milosev ◽  
N. Manojlovic ◽  
...  
Keyword(s):  
Biological Activity ◽  
Nmr Spectroscopy ◽  
Structural Analysis ◽  
1H Nmr ◽  
1H Nmr Spectroscopy ◽  
Chemical Structure ◽  
High Yield ◽  
Thiourea Derivatives ◽  
Starting Compound ◽  
Derivatives Of

Aminothiazole derivatives of 4-hydroxy-2H-chromen-2-one were prepared by the Hantzsch reaction1 using 3-(2-bromoacetyl)-4-hydroxy-2H-chromen-2-one and thiourea derivatives. Starting compound for this synthesis 3-(2-bromoacetyl)-4-hydroxy- 2H-chromen-2-one (1) was prepared previously.2 Also, for this synthesis we used thiourea derivatives (2a-j) as compounds which possess groups with biological activity. Reactions are carried out in refluxing ethanol for a period of 30 - 45 min. Final products (3a-j) are obtained in a high yield. Chemical structure of the obtained compounds was confirmed by elemental and structural analysis (IR and 1H NMR spectroscopy).

scholarly journals Tổng hợp polymer quang dẫn poly(4-diphenylamino styrene) cho vật liệu quang phi tuyến

2019 ◽  
Vol 14 (3) ◽  
pp. 18
Author(s):  
Nguyễn Hữu Vinh ◽  
Nguyễn Thế Mạnh ◽  
Nguyễn Thị Thúy Hồng ◽  
Bạch Long Giang ◽  
Giang Ngọc Hà
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Nmr Spectroscopy ◽  
1H Nmr Spectroscopy ◽  
Chemical Structure ◽  
Proton Nuclear Magnetic Resonance ◽  
White Crystal ◽  
Synthesis Procedure ◽  
The University ◽  
Wittig Reagent ◽  
University Laboratory

The typical synthesis procedure for the monomer of N,N-diphenyl-4-vinylaniline was conducted and has been proved to be ineffective in the university laboratory conditions. The modified procedure was applied successfully using freshly formed Wittig reagent. The monomer was characterized by proton nuclear magnetic resonance (1H NMR) spectroscopy and confirmed the chemical structure with the correct peaks. The photoconductive polymer of poly((4-diphenylamino styrene)) could be obtained only by using the white crystal monomer.

Asymetrical Dimer - allyl-palladiu Complexes II. Data from Infrared Spectra and Chemical Behaviour

2008 ◽  
Vol 59 (7) ◽  
Author(s):  
Maria Maganu ◽  
Filip Chiraleu ◽  
Constantin Draghici ◽  
Gheorghe Mihai
Keyword(s):  
Carbon Monoxide ◽  
Nmr Spectroscopy ◽  
1H Nmr ◽  
Infrared Spectra ◽  
Analytical Methods ◽  
1H Nmr Spectroscopy ◽  
Chemical Behaviour ◽  
The Asymmetry ◽  
Pd Complexes

The previous data obtained by 1H-NMR spectroscopy established the existence of an asymmetry of the bond between Pd and p-allylic groups, even in the p-allyl-Pd complexes dimers which are considered usually symmetric dimers. The asymmetry of the bond depends by the substitutes of the allylic group. Other analytical methods were investigated for additional proof of the obtained results. Thus, this paper discusses how this asymmetry would be reflected in the infrared spectra and in the reaction of the complexes with carbon monoxide.

Diastereoselective Reduction of Selected α-substituted β-keto Esters and the Assignment of the Relative Configuration by 1H-NMR Spectroscopy

2020 ◽  
Vol 07 ◽  
Author(s):  
Christian Trapp ◽  
Corinna Schuster ◽  
Chris Drewniok ◽  
Dieter Greif ◽  
Martin Hofrichter
Keyword(s):  
Nmr Spectroscopy ◽  
1H Nmr ◽  
1H Nmr Spectroscopy ◽  
Selective Reduction ◽  
Reducing Agents ◽  
Relative Configuration ◽  
Curtius Rearrangement ◽  
Keto Esters ◽  
Hydroxy Esters ◽  
Diastereoselective Reduction

Background:: Chiral β-hydroxy esters and α-substituted β-hydroxy esters represent versatile building blocks for pheromones, β-lactam antibiotics and 1,2- or 1,3-aminoalcohols. Objective:: Synthesis of versatile α-substituted β-keto esters and their diastereoselective reduction to the corresponding syn- or anti-α-substituted β-hydroxy esters. Assignment of the relative configuration by NMR-spectroscopy after a CURTIUS rearrangement of α-substituted β-keto esters to 4-substituted 5-methyloxazolidin-2-ones. Method:: Diastereoselective reduction was achieved by using different LEWIS acids (zinc, titanium and cerium) in combination with complex borohydrides as reducing agents. Assignment of the relative configuration was verified by 1H-NMR spectroscopy after CURTIUS-rearrangement of α-substituted β-hydroxy esters to 4-substituted 5-methyloxazolidin-2-ones. Results:: For the syn-selective reduction, titanium tetrachloride (TiCl4) in combination with a pyridine-borane complex (py BH3) led to diastereoselectivities up to 99% dr. High anti-selective reduction was achieved by using cerium trichloride (CeCl3) and steric hindered reducing agents such as lithium triethylborohydride (LiEt3BH). After CURTIUS-rearrangement of each α-substituted β-hydroxy ester to the corresponding 4-substituted 5-methyloxazolidin-2-one, the relative configuration was confirmed by 1H NMR-spectroscopy. Conclusion:: We have expanded the procedure of LEWIS acid-mediated diastereoselective reduction to bulky α-substituents such as the isopropyl group and the electron withdrawing phenyl ring.

Conformational study on ribonucleoside O-phosphonylmethyl derivatives by 1H NMR spectroscopy

1985 ◽  
Vol 50 (8) ◽  
pp. 1899-1905 ◽  
Author(s):  
Milena Masojídková ◽  
Jaroslav Zajíček ◽  
Miloš Buděšínský ◽  
Ivan Rosenberg ◽  
Antonín Holý
Keyword(s):  
Nmr Spectroscopy ◽  
1H Nmr ◽  
1H Nmr Spectroscopy ◽  
Conformational Study ◽  
H Nmr ◽  
Conformational Properties

Conformational properties of ribonucleoside 5'-O-phosphonylmethyl derivatives have been determined by 1H NMR spectroscopy and compared with those of natural nucleosides and 5'-nucleotides.

scholarly journals Resolving Entangled JH-H-Coupling Patterns for Steroidal Structure Determinations by NMR Spectroscopy

Molecules ◽  
2021 ◽  
Vol 26 (9) ◽  
pp. 2643
Author(s):  
Danni Wu ◽  
Kathleen Joyce Carillo ◽  
Jiun-Jie Shie ◽  
Steve S.-F. Yu ◽  
Der-Lii M. Tzou
Keyword(s):  
Nmr Spectroscopy ◽  
1H Nmr Spectroscopy ◽  
Chemical Shifts ◽  
Atomic Level ◽  
Molecular Structures ◽  
Naturally Occurring ◽  
Structure Determinations ◽  
Ligand Interactions ◽  
Synthetic Steroids ◽  
The Individual

For decades, high-resolution 1H NMR spectroscopy has been routinely utilized to analyze both naturally occurring steroid hormones and synthetic steroids, which play important roles in regulating physiological functions in humans. Because the 1H signals are inevitably superimposed and entangled with various JH–H splitting patterns, such that the individual 1H chemical shift and associated JH–H coupling identities are hardly resolved. Given this, applications of thess information for elucidating steroidal molecular structures and steroid/ligand interactions at the atomic level were largely restricted. To overcome, we devoted to unraveling the entangled JH–H splitting patterns of two similar steroidal compounds having fully unsaturated protons, i.e., androstanolone and epiandrosterone (denoted as 1 and 2, respectively), in which only hydroxyl and ketone substituents attached to C3 and C17 were interchanged. Here we demonstrated that the JH–H values deduced from 1 and 2 are universal and applicable to other steroids, such as testosterone, 3β, 21-dihydroxygregna-5-en-20-one, prednisolone, and estradiol. On the other hand, the 1H chemical shifts may deviate substantially from sample to sample. In this communication, we propose a simple but novel scheme for resolving the complicate JH–H splitting patterns and 1H chemical shifts, aiming for steroidal structure determinations.

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