Monovalent compounds

The first work on pKa determination by zone electrophoresis using paper strips was described by Waldron-Edward in 1965 (15). Also, Kiso et al. in 1968 showed the relationship between pH, mobility, and p/C, using a hyperbolic tangent function (16). Unfortunately, these methods had not been widely accepted because of the manual operation and lower reproducibility of the paper electrophoresis format. The automated capillary electrophoresis (CE) instrument allows rapid and accurate pKa determination. Beckers et al. showed that thermodynamic pATt, (pATf) and absolute ionic mobility values of several monovalent weak acids were determined accurately using effective mobility and activity at two pH points (17). Cai et al. reported pKa values of two monovalent weak bases and p-aminobenzoic acid (18). Cleveland et al. established the thermodynamic pKa determination method using nonlinear regression analysis for monovalent compounds (19). We derived the general equation and applied it to multivalent compounds (20). Until then, there were many reports on pKa determination by CE for cephalosporins (21), sulfonated azo-dyes (22), ropinirole and its impurities (23), cyto-kinins (24), and so on. 

Monovalent compounds of the higher members of group 13 tend not to be stable. However, such species have been proposed as reaction intermediates see Aluminum Inorganic Chemistry and Boron Hydrides). Thus, the reaction, discovered by Alfred Stock, in which B2CI4 may be produced by the zinc discharge reduction of BCI3, is believed to proceed via the intermediacy of BCl, which inserts into a B-Cl bond of a second BCI3 molecule ... 

Many of the monovalent and divalent compounds, such as AEG40730 [258], also bind with high affinity to cIAPl and cIAP2. Several compounds of both classes have shown efficacy in preclinical cancer models as both single agents and as potentiators of other therapies. Six compounds have entered clinical trials in the last few years. Though divalent inhibitors are expected to be intravenously delivered, two presumably monovalent compounds were dosed orally in Phase I trials. 

As evidence for the efficacy of the pan-specific monovalent compounds accumulated, parallel studies supported the potential for bivalent molecules with increased potency. However, the two classes have pharmacological properties that must be taken into consideration for clinical development. 

Monovalent compounds of the higher members of group 13 tend not to be stable. However, such species have been proposed as reaction intermediates (5ee Aluminum Inorganic Chemistry and Boron Hydride. Thus, the... 

To treat the analog of the charge-transfer exciton in azides, Equation (5) must be generalized because of complications arising from the nonspherical azide ion. Again being specific to monovalent compounds,... 

Three nonalkali cations which form simple monovalent compounds with the azide ion are Tl, Ag, and Cu. From the lattice parameters of Weir and coworkers [74] for TIN3, one can compute the contact radius for the azide ion to be 1.50 A. Comparison with the value 1.63 A found in the alkali azides belonging to the same crystal class as TIN3 indicates some departure from ionicity. The corresponding values 1.30 A and 1.27 A for AgN3 and CUN3 indicate a considerable degree of covalence for them. 

FIGURE 4.6 Dependence of the effective mobilities of a monovalent compound (LY334370) on pH. Arrow indicates the pH equal to the p a- (From Caliaro GA., Herbots C.A., J. Pharm. Biomed. Anal., 26, 427 34, 2001.)... 

The French chemist undoubtedly studied thallium in much greater detail than W. Crookes. He showed that the metal formed trivalent and monovalent compounds. Monovalent thallium has much in common with alkali metals trivalent thallium resembles aluminium. J. Dumas named it the paradoxical metal . It was the similarity of thallium with sodium and potassium that gave rise to the idea that thallium was a mixture of unknown alkali metals with large atomic masses. It is regrettable that all the credit for the discovery of thallium is given to W. Crookes, while the French chemist s significant achievements are often ignored. 

Gemini surfactants show greatly enhanced surfactant properties relative to the corresponding monovalent compounds, which makes them of special interest for biomedical applications. In the last 10 years different gemini cationic surfactants with amino acids... 

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