Effects of Polar Substituents and Media on the Performance ofN,N′‐Di‐tert‐Butoxycarbonyl‐Indigos as Photoswitches

ChemPhotoChem ◽  
2019 ◽  
Author(s):  
Benjamin Koeppe ◽  
Vincent R. F. Schröder
Keyword(s):  
Polar Substituents

scholarly journals Adjustment of Hydrophobic Properties of Cellulose Materials

Polymers ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1241
Author(s):  
Michael Ioelovich
Keyword(s):  
Ester Group ◽  
Hydroxyl Groups ◽  
Chemical Methods ◽  
Hydrophobic Properties ◽  
Cellulose Esters ◽  
Cellulose Modification ◽  
Polar Groups ◽  
Polar Substituents ◽  
Hydrolysis Of ◽  
Cellulose Materials

In this study, physicochemical and chemical methods of cellulose modification were used to increase the hydrophobicity of this natural semicrystalline biopolymer. It has been shown that acid hydrolysis of the initial cellulose increases its crystallinity, which improves hydrophobicity, but only to a small extent. A more significant hydrophobization effect was observed after chemical modification by esterification, when polar hydroxyl groups of cellulose were replaced by non-polar substituents. The esterification process was accompanied by the disruption of the crystalline structure of cellulose and its transformation into the mesomorphous structure of cellulose esters. It was found that the replacement of cellulose hydroxyls with ester groups leads to a significant increase in the hydrophobicity of the resulting polymer. Moreover, the increase of the number of non-polar groups in the ester substituent contributes to rise in hydrophobicity of cellulose derivative. Depending on the type of ester group, the hydrophobicity increased in the following order: acetate < propionate < butyrate. Therefore, tributyrate cellulose (TBC) demonstrated the most hydrophobicity among all studied samples. In addition, the mixed ester, triacetobutyrate cellulose (TAB), also showed a sufficiently high hydrophobicity. The promising performance properties of hydrophobic cellulose esters, TBC and TAB, were also demonstrated.

ChemInform Abstract: 2,4-Bis(4-aryl-1,2,3-triazol-1-yl)pyrrolo[2,3-d]pyrimidines: Synthesis and Tuning of Optical Properties by Polar Substituents.

ChemInform ◽  
2015 ◽  
Vol 46 (36) ◽  
pp. no-no
Author(s):  
Jonas Bucevicius ◽  
Lina Skardziute ◽  
Jelena Dodonova ◽  
Karolis Kazlauskas ◽  
Gintautas Bagdziunas ◽  
...  
Keyword(s):  
Optical Properties ◽  
Polar Substituents

scholarly journals Synthesis, Characterization and Unusual Dielectric Behaviour of λ-Shaped Mesogenic Homologous Series With Polar Substituents

2011 ◽  
Vol 2 ◽  
pp. 16-25 ◽  
Author(s):  
P. B. Chand ◽  
R. Manohar
Keyword(s):  
Activation Energy ◽  
Homologous Series ◽  
Dielectric Behaviour ◽  
Scanning Calorimetry ◽  
Oh Groups ◽  
Smectic C ◽  
Specific Shape ◽  
Polar Substituents ◽  
Derivatives Of ◽  
Conformer Model

A new λ-shaped mesogenic homologous series with polar bromo and nitro substituent was synthesized by fixing rigid 2-bromo-4-nitrophenylazo groups to a resorcinol moiety. 4-n-alkoxybenzoyl groups esterify both the phenolic -OH groups. In the present series, methoxy and ethoxy derivatives are non-mesogenic, n-propyloxy to n-octyloxy derivatives exhibit enantiotropic nematic mesophase. Smectic C (SmC) mesophase commences from the n- octyloxy derivative as an enantiotropic phase and is retained up to the last member synthesized. The effect of polar bromo and nitro substituent on mesomorphic properties is discussed. In this paper, we also report the unusual dielectric behaviour of n-octyloxy and n-tetradecyloxy derivatives of the present λ-shaped mesogenic homologous series. The dielectric permittivity of the sample was found to be unusually low in SmC phase in comparison to nematic phase. We have explained it on the basis of two-conformer model, which can exist in SmC phase due to specific shape of the molecule. The model has been supported by calculating activation energy of both the possible conformers from Arrhenius plot of relaxation frequency versus temperature. There is a clear difference in the value of activation energy of both the conformers as expected.Keywords: C. Differential scanning calorimetry (DSC); D. Dielectric properties; D. Phase transitionsThe Himalayan Physics  Vol.2, No.2, May, 2011Page: 16-25Uploaded Date: 31 July, 2011

scholarly journals Molluscicidal activity of 2-hydroxy-[1,4]naphthoquinone and derivatives

2008 ◽  
Vol 80 (2) ◽  
pp. 329-334 ◽  
Author(s):  
Celso A. Camara ◽  
Tania M.S. Silva ◽  
Thiago G. da-Silva ◽  
Rodrigo M. Martins ◽  
Ticiano P. Barbosa ◽  
...  
Keyword(s):  
Brine Shrimp ◽  
General Rule ◽  
Biomphalaria Glabrata ◽  
Artemia Salina ◽  
World Health ◽  
Significant Toxicity ◽  
The World ◽  
Health Organization ◽  
Polar Substituents ◽  
Molluscicidal Activity

The toxic profile of lawsone (2-hydroxy-[1,4]naphthoquinone) and a series of [1,4]naphthoquinone derivatives was evaluated against the brine shrimp Artemia salina and against the mollusk Biomphalaria glabrata, the main transmitting vector of schistosomiasis in Brazil. Of the seventeen compounds tested nine fell below the threshold of 100 µg/mL set for potential molluscicidal activity by the World Health Organization. As a general rule derivatives with non-polar substituents presented the highest molluscicidal activities. These substances showed significant toxicity in A. salina lethality bioassay.

ChemInform Abstract: Liquid-Crystalline Imidazo(2,1-b)-1,3,4-thiadiazoles. Part 3. Synthesis and Dielectric Properties of Imidazo(2,1-b)-1,3,4-thiadiazoles with Polar Substituents.

ChemInform ◽  
1988 ◽  
Vol 19 (48) ◽  
Author(s):  
S. I. TORGOVA ◽  
N. M. SHTYKOV ◽  
A. G. ABOLIN ◽  
L. A. KARAMYSHEVA ◽  
A. V. IVASHCHENKO ◽  
...  
Keyword(s):  
Dielectric Properties ◽  
Liquid Crystalline ◽  
Polar Substituents

scholarly journals The Development of Novel Organotin Anti-Tumor Drugs: Structure and Activity

1998 ◽  
Vol 5 (4) ◽  
pp. 179-188 ◽  
Author(s):  
Dick de Vos ◽  
Rudolph Willem ◽  
Marcel Gielen ◽  
Kyra E. van Wingerden ◽  
Kees Nooter
Keyword(s):  
Water Solubility ◽  
Solubility In Water ◽  
In Vivo Testing ◽  
Polar Substituents ◽  
Tumor Drugs ◽  
Separate Class ◽  
Structure And Activity ◽  
Very High

An overview of the development of anti-tumor organotin derivatives in selected classes of compounds is presented and discussed. High to very high in vitro activity has been found, sometimes equaling that of doxorubicin. Solubility in water is an important issue, dominating the in vivo testing of compounds with promising in vitro properties. The cytotoxicity of the compounds was increased by the presence of a bulky group, an active substituent or one or more polar substituents. Polar substituents may also improve the water solubility. Although organotin derivatives constitute a separate class of compounds, the comparison with cisplatin is inevitable. Among the observed toxicities, neurotoxicity, known from platinum cytostatics, and gastrointestinal toxicity, typical for many oncology drugs, have been detected. Further research to develop novel, useful organotin anti-tumor compounds should be carried out.

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