Connector Links for CPK Atomic Models
The marked superiority of the CPK Atomic Models derives largely from Dr. Koltun’s Connector Links. His analysis of the engineering problems involved led him to combine new plastic materials with innovative link designs which satisfy four critical requirements simultaneously:
- Hold atoms together with great tenacity. A force of 5 to 7 kg is required to separate them. This force is readily furnished by the levering blade of the PY2 67-7120 Construction Tool.
- Permit distortions of bond angles to vary up to ±8° with negligible loss in bond strength.
- Develop sufficient rotational friction to assure that large, extended side chains, often attached by a single bond, will remain indefinitely in proper steric orientation.
- Allow bond distances to be shortened or lengthened. The connectors are made of Texin®, a hard, rubber-like elastomer which is strong but resilient and flexible.
Since bond distances and angles for particular atoms are known to vary even in similar structures, two special links, in addition to the standard link, are provided to increase or decrease the normal bond distance by +0.08Å or -0.05Å. A special ’gluing’ link is also available for permanently connecting atoms at standard bond distances. The various link types are color-coded to aid identification.