Preferred Label : isomorphous structures;
Detailed label : isomorphous structures in polymers;
IUPAC definition : In the crystalline state, polymer chains are generally parallel to one another but
neighbouring chains of equivalent conformation may differ in chirality and/or orientation.
Chains of identical chirality and conformation are isomorphous. Chains of opposite
chirality but equivalent conformation are enantiomorphous. For example, two ...TG
sup /sup TG sup /sup TG sup /sup ... helices of isotactic poly(propylene) are
isomorphous. Isotactic poly(propylene) chains of the ...TG sup /sup TG sup /sup
TG sup /sup ... and ...G sup /sup TG sup /sup TG sup /sup T... types are mutually
enantiomorphous. With regard to orientation, consider a repeating side group originating
at atom A1i, the first atom of the side group being Bαi. For certain chain symmetries
(helical, for instance) the bond vectors b( ) (A1i/Bαi) have the same components (positive
or negative) b( )·c( )/ c( ) along the i c /i axis for every i. Two equivalent
(isomorphous or enantiomorphous) chains in the crystal lattice, having identical components
of the bond vectors along i c /i , both positive or both negative, are designated
isoclined; two equivalent chains having bond vectors along i c /i of the same magnitude
but opposite sign are designated anticlined.;
Origin ID : I03299;
See also
In the crystalline state, polymer chains are generally parallel to one another but
neighbouring chains of equivalent conformation may differ in chirality and/or orientation.
Chains of identical chirality and conformation are isomorphous. Chains of opposite
chirality but equivalent conformation are enantiomorphous. For example, two ...TG
sup /sup TG sup /sup TG sup /sup ... helices of isotactic poly(propylene) are
isomorphous. Isotactic poly(propylene) chains of the ...TG sup /sup TG sup /sup
TG sup /sup ... and ...G sup /sup TG sup /sup TG sup /sup T... types are mutually
enantiomorphous. With regard to orientation, consider a repeating side group originating
at atom A1i, the first atom of the side group being Bαi. For certain chain symmetries
(helical, for instance) the bond vectors b( ) (A1i/Bαi) have the same components (positive
or negative) b( )·c( )/ c( ) along the i c /i axis for every i. Two equivalent
(isomorphous or enantiomorphous) chains in the crystal lattice, having identical components
of the bond vectors along i c /i , both positive or both negative, are designated
isoclined; two equivalent chains having bond vectors along i c /i of the same magnitude
but opposite sign are designated anticlined.
