Page 427 - Carrahers_Polymer_Chemistry,_Eighth_Edition

390 Carraher’s Polymer Chemistry

Some of the organotin-containing polymers selectively inhibit Candias albicans, the yeast
responsible for yeast infections in men and women better than commercially available applica-

tions while leaving the normal flora unharmed. Others preferentially inhibit methicillin-resistant
Staphylococcus aureus (MRSA), 11.22.

R
R
R 1
O
(11.22)
Sn
R R 1
1
Organotin polyamines containing the plant growth hormone kinetin (11.23) increases the ger-
mination of damaged seeds and thus it may help in providing food in third world countries. It also
increases the germination rate of sawgrass seed from about 0% to more than 50% and may become
an important agent in replenishing the “sea of grass” (actually sawgrass) in the Everglades.

O

R 1
R
Sn
N
R 1 (11.23)
N
N

N
N
R

Carraher and Battin recently reported the discovery of metal-containing polymers based on
Group IVB metallocenes reacted with diamines where the conductivity was increased by as much
7
as 10 through simple doping with iodine. Thus, such materials may have use as electrically con-
ductive materials (Figure 11.1).

11.4 COORDINATION POLYMERS

Coordination polymers have served humankind since before recorded history. The tanning of
leather and generation of selected colored pigments depend on the coordination of metal ions.
A number of biological agents, including plants and animals, owe their existence to coordinated
polymers such as hemoglobin. Many of these coordination polymers have unknown and/or irreg-
ular structures.
The drive for the synthesis and characterization of synthetic coordination polymers was cata-
lyzed by work supported and conducted by the United States Air Force in a search for materials
that exhibited high thermal stabilities. Attempts to prepare highly stable, tractable coordination
polymers were disappointing. Typically, only oligomeric products were formed and the monomeric
versions were often more stable than the polymeric versions.
Bailar listed a number of principles that can be considered in designing coordination polymers.
Briefly these are as follows: (1) Little flexibility is imparted by the metal ion or within its immediate

environment; thus, flexibility must arise from the organic moiety. Flexibility increases as the cova-

lent nature of metal–ligand bond increases. (2) Metal ions only stabilize ligands in their immediate

9/14/2010 3:41:39 PM
K10478.indb 390
K10478.indb 390 9/14/2010 3:41:39 PM