Molecular Assemblies Header
Dr. Gutow's Molecular Assemblies Site
On the left in the table below you can view some rotatable 3-D images of assemblies of molecules using JSmol. Select the assembly to view using the menu to the right.
Choose an Assembly:
Molecular assemblies are held together by relatively strong intermolecular forces. 

In the case of water the dominant interactions are hydrogen bonding and dipole-dipole interactions.  In ice the hydrogen bonding results in a rigid stucture where each water has the same orientation relative to its neighbors.  In melting ice, many of the hydrogen bonds are ruptured and less order is apparent.  Notice that ice has large holes between the molecules; thus ice has a larger volume than the same amount of liquid water.

In the case of lipid bilayers (cell membranes are an example) one of the dominant interactions is the van der Waals attractions between the long alkyl tails of the lipids.  The structure of the lipid bilayer also depends on the polar interactions between the water at each side of the bilayer and the polar head groups.
Instructions for using Jmol/JSmol:
  1. Choose which assembly to display by selecting it in the popup menu.
  2. ROTATE the image by holding down the mouse button while moving the cursor over the image. 
  3. ZOOM by holding down the shift key while moving the cursor up (decrease magnification) or down (increase magnification) on top of the image. 
  4. Other options are available in the control menu accessible by holding the mouse button down while the cursor is over "Jmol" in the lower right corner (right click also works on a multibutton mouse). 
  5. For more info about Jmol go to