Crystal engineering polymerization

A most interesting extension of this type of reaction was performed by Addadi and Lahav (175). Their aim was to obtain chiral polymers by performing die reaction in a crystal of chiral structure. They employed monomers 103. The initial experiments were with a chiral resolved 103 where R1 is (R)- or ( -sec-butyl and R2 is C2H3. This material indeed crystallizes in the required structure, and yields photodimers and polymers with the expected stereochemistry, and with quantitative diastereomeric yield. It was possible to establish that the asymmetric induction was due essentially only to the chirality of the crystal structure and not to direct influences of the sec-butyl. Subsequently they were able, using sophisticated crystal engineering, to obtain chiral crystals from nonchiral 103, and from them dimers and polymers with high, probably quantitative enantiomeric yields. This may be described as an absolute asymmetric polymerization. 

Keywords Crystal engineering Solid-state photoreaction Topochemical polymerization Controlled radical polymerization Dimerization Isomerization Topotactic reaction... 

The topochemical polymerization of 1,3-diene monomers based on polymer crystal engineering can be used not only for tacticity but also for the other chain structures such as molecular weight [ 102], ladder [84] or sheet [ 103] structures, and also polymer layer structures using intercalation reactions [ 104-107]. Some mechanical and structural properties have already been revealed with well-defined and highly or partly crystalline polymers [ 108-111 ]. A totally solvent-free system for the synthesis of layered polymer crystals was also reported [112]. 

Molecular-beam epitaxy, for semiconductor growth, with Group 3 nitrides, 12, 4-5 Molecular gyroscopes, via iron carbonyls, 6, 51 Molecular mass distributions, in olefin polymerization, 4,1113 Molecular materials, and crystal engineering, 12, 555 Molecular mechanics future directions, 1, 666 in hybrid computational chemistry, 1, 664 Rh-catalyzed hydroformylation, 7, 239 Molecular modeling, arene chromium tricarbonyls, 5, 255 Molecular orbitals, and photoelectron spectroscopy variations,... 

Another major area of CSD-based research is the supramolecular stmctural organization and crystal engineering, and particularly the role of hydrogen bonding in the solid state. Although fhe initial incentive came from biomolecular chemistry, fhe results are equally important for inorganic, organometallic, and polymeric materials. 

Owing to the enormous range of what can now be described as supramolecular chemistry, the present work will chiefly focus on discrete molecular assemblies. In particular, no attempt has been made to discuss the burgeoning field d of crystal engineering . Similarly, unless of particular relevance to the topic under discussion, higher oligomeric and polymeric systems, including most metal cluster and related compounds, have also been excluded from the discussion. 

Matsumoto, A., Nagahama, S. and Odani, T. (2000) Molecular design and polymer structure control based on polymer crystal engineering. Topochemical polymerization of 1,3-diene mono- and dicarboxylic acid derivatives bearing a naphthylmethylammonium group as the countercation. J. Am. Chem. Soc., 122, 9109-9119. 

Matsumoto, A., Tanaka, T., Tsubouchi, T., Tashiro, K., Saragai, S. and Nakamoto, S. (2002) Crystal engineering for topochemical polymerization of muconic esters using halogen-halogen and CH/jt interactions as weak intermolecular interactions. J. Am. Chem. Soc., 124, 8891-8902. 

The construction of novel coordination polymers is a current interest in the field of supramolecular chemistry and crystal engineering, stemming from their potential applications as frinctional materials as well as their intriguing variety of architectures and molecular topologies. In particular, solid materials with either helical or chiral structures are of intense interest in chemistry and material science. Although solid materials with imusual structures are expected to increase in number, the exploration for preparing framework solids with chiral structures still remains a challenge. Thermal analysis is a fundamental tool for the characterization of these new coordination polymeric compounds. 

These results suggest that a careful and precise engineering of the crystalline morphology in one-dimensional nanostructures consisting of semicrystalline polymers is indispensable for the optimization of their performance as device components in real-life applications. Furthermore, the investigation of the crystallization in polymeric nanotubes and nanorods aligned in the nanopores of rigid hard templates is complementary to studies on the crystallization of semicrystalline blocks in microphase-separated... 

---