Large structural moieties

In the search for new drug candidates, scientists use molecular modeling techniques to identify potentially new structural moieties and screen natural sources or large families of synthetically related compounds, along with modifying exisiting compounds. Once a potentially new drug has been iden-... 

A critical structural issue with the subsequent incorporation of this type of chromophore-modified nucleosides into DNA duplexes is the assumption that it forms Watson-Crick base pairs with A as the counterbase. Our concern was that the large pyrene moiety may force the nucleosides into a syn conformation. 

Since the twins provide excellent models for investigation of LCP behavior, let us first consider 9AZA9 and 9DDA9. If we use an empirical group additivity approach to the calculation of the heat capacity increase at Tg, by dividing the molecule into mobile structural moieties ("beads") with a contribution of 11.3 J/Kmol for a small "bead" (-CH2-, -CO2-, etc) and approximately twice that amount for "large" beads (-Ph-for example), (19-201 the "expected" values are observed for a number of conventional low molecular mass nematic glasses such as 4-butyl-4 -methoxyazoxybenzene, a close... 

The data presented in this review testify to the appearance of a large series of novel bis(naphthalic anhydrides). These monomers are characterized by structural moieties which determine an enhanced solubility (and processability) of the derived polyheteroarylenes. Bis(naphthalic anhydrides) with ether groups may be employed in the preparation of systems similar to polyetheramides but having higher glass transition temperatures. The majority of novel bis(naphthalic anhydrides) may be used in the preparation of novel poly-naphthoylenebenzimidazoles which combine satisfactory processability with very high thermal and chemical stability. 

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