The Investigation of Complexation Properties and Hard-Soft Acid-Base Relationship Between Thiacrown Ethers and Metal Ions

2016 ◽  
Vol 13 (8) ◽  
pp. 572-577 ◽  
Author(s):  
Baki Çiçek ◽  
Ümit Çalışır
Keyword(s):  
Metal Ions ◽  
Acid Base ◽  
Thiacrown Ethers ◽  
Soft Acid

An analysis of the factors contributing to the regioselectivity observed in the opening of oxiranes

1980 ◽  
Vol 58 (3) ◽  
pp. 302-306 ◽  
Author(s):  
Margaret M. Kayser ◽  
Peter Morand
Keyword(s):  
Oxygen Atom ◽  
Ring Opening ◽  
Oxirane Ring ◽  
Epoxide Ring ◽  
Acid Base ◽  
Epoxide Ring Opening ◽  
Soft Acid ◽  
Hsab Theory

The regioselectivity of epoxide ring opening can be analyzed in terms of hard–soft acid–base (HSAB) theory. The coordination of the hard acid with the oxygen atom of the oxirane ring produces a "pulling effect" which determines the direction of the ring opening. In the absence of a strong "pulling effect" the "pushing effect" of the approaching base is examined and the consequences of relative softness or hardness of the nucleophile on the regioselectivity of the ring opening are discussed.

Preparation and properties of some rare-earth phthalocyanines

1974 ◽  
Vol 27 (5) ◽  
pp. 955 ◽  
Author(s):  
AG MacKay ◽  
JF Boas ◽  
GJ Troup
Keyword(s):  
Rare Earth ◽  
Metal Ions ◽  
Spectral Properties ◽  
Magnetic Moments ◽  
Anionic Form ◽  
Rare Earth Compounds ◽  
Acid Base ◽  
Polymeric Form ◽  
Acid Base Equilibrium ◽  
Trivalent Rare Earth

The preparations and magnetic and spectral properties of one ytterbium and two gadolinium phthalocyanines are described and comparisons made with previous studies. The susceptibility of all three compounds followed a Curie-Weiss law, with � small, and the magnetic moments were typical for trivalent rare-earth compounds with little or no coupling between the metal ions. The e.p.r. signals observed were due to the metal ions. Structures proposed are Cl(pc)YbCl,2H2O (where pc = C32H16N8) for ytterbium, and (pc)Gd(pc)H and an associated anionic form for gadolinium. Both gadolinium materials are stable under certain solution conditions, although the anionic material tends to decompose and is difficult to obtain from solution. A polymeric form of phthalonitrile (m.p. 306�C) was isolated during purification. A simple acid-base equilibrium is proposed for the gadolinium compounds but it is complicated by the separation procedures and by the nature and purity of the solvent.

scholarly journals Lead Oxide-Graphite Composite Electrode for pH Measurement

2015 ◽  
Vol 15 (1) ◽  
pp. 61-66
Author(s):  
Ranjan Nepal ◽  
Raja Ram Pradhananga
Keyword(s):  
Metal Ions ◽  
Lead Oxide ◽  
Composite Electrode ◽  
Low Cost ◽  
Potential Gradient ◽  
Ph Measurement ◽  
Indicator Electrode ◽  
Quick Response ◽  
Acid Base ◽  
Graphite Composite

Lead oxide-graphite composite electrode for pH measurement had been fabricated with different percentage of PbO2 in the composite. The proportions of lead oxide affected the sensitivity of the electrode. The electrode composed of 50% lead oxide and 50% graphite gave reproducible result and behaved in Nernstian manner with a potential gradient of -58.8±0.3 mV per unit change in pH. Metal ions such as iron (II), iron (III) and lead (II) interfered in the measurement of pH, while silver (I), copper (II), oxidizing agents such as dichromate and permanganate do not interfere. In absence of interfering ion, the lead oxide-graphite composite electrode could be used for the measurement of pH from 2 to 11. This electrode can also be used as an indicator electrode for acid base titrations. Low cost, quick response, easy to fabricate are some of the advantages of the lead oxide-graphite composite electrode. This electrode is also found to be sensitive to Pb2+ -ions and can be used as a Pb2+-ion sensor up to 10-4M.DOI: http://dx.doi.org/10.3126/njst.v15i1.12015  Nepal Journal of Science and TechnologyVol. 15, No.1 (2014) 61-66

scholarly journals Imparting gas selective and pressure dependent porosity into a non-porous solid via coordination flexibility

2019 ◽  
Vol 6 (9) ◽  
pp. 1883-1891 ◽  
Author(s):  
Shyamapada Nandi ◽  
Phil De Luna ◽  
Rahul Maity ◽  
Debanjan Chakraborty ◽  
Thomas Daff ◽  
...  
Keyword(s):  
Porous Solid ◽  
Acid Base ◽  
Base Concept ◽  
Soft Acid

Using a simple hard–soft acid–base concept we have deliberately designed gas-specific and pressure dependent porosity into a non-porous solid via coordination flexibility.

Thermogravimetric Studies on Bimetallic Dithiocarbamate Complexes

1992 ◽  
Vol 47 (9) ◽  
pp. 1297-1299 ◽  
Author(s):  
G. S. Sodhi ◽  
J. Kaur
Keyword(s):  
Activation Energy ◽  
Thermal Decomposition ◽  
Decomposition Reaction ◽  
Activation Entropy ◽  
Acid Base ◽  
Thermal Stabilities ◽  
Tg Studies ◽  
Thermogravimetric Studies ◽  
Soft Acid ◽  
Hsab Theory

Thermogravimetric (TG) studies have been carried out for some bimetallic dithiocarbamate complexes of the type ZnML4 and NiM′L′4 [M = Co(II), Cu(II); M′ = Zn(II), Hg(II); L = N-methylcyclohexyldithiocarbamate; L′ = N-ethylcyclohexyldithiocarbamate]. From TG curves, the order, apparent activation energy and apparent activation entropy for the thermal decomposition reaction have been calculated. The thermal stabilities have been correlated with the structures of the complexes on the basis of hard and soft acid base (HSAB) theory.

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