Molecular self-assembly is the spontaneous association of molecules under equilibrium conditions into stable, structurally well-defined aggregates joined by noncovalent bonds. Molecular self-assembly is ubiquitous in biological systems and underlies the formation of a wide variety of complex biological structures. Understanding self-assembly and the associated noncovalent interactions that connect complementary interacting molecular surfaces in biological aggregates is a central concern in structural biochemistry. Self-assembly is also emerging as a new strategy in chemical synthesis, with the potential of generating nonbiological structures with dimensions of 1 to 10(2) nanometers (with molecular weights of 10(4) to 10(10) daltons). Structures in the upper part of this range of sizes are presently inaccessible through chemical synthesis, and the ability to prepare them would open a route to structures comparable in size (and perhaps complementary in function) to those that can be prepared by microlithography and other techniques of microfabrication.

Molecular self-assembly and nanochemistry: A chemical strategy for the synthesis of nanostructures

Department of Pharmaceutics, National Institute of Pharmaceutical Education and Research (NIPER), Sector 67, S. A. S. Nagar,Mohali, Punjab-160 062, India, Institute of Biochemistry, Faculty of Medicine, Polytechnic University, Via Ranieri 67, IT-60100 Ancona, Italy,Green Biotechnology Research Group, The Special Division for Human Life Technology, National Institute of Advanced Industrial Science andTechnology, 1-8-31 Midorigaoka, Ikeda, Osaka-563-8577, Japan, and Department of Medicinal Chemistry & Natural Products,The Hebrew University of Jerusalem, School of Pharmacy-Faculty of Medicine, Jerusalem 91120, IsraelReceived March 2, 2004

Chitosan chemistry and pharmaceutical perspectives.

About Dendrimers: Structure, Physical Properties, and Applications

This Account reports the synthesis and characterization of dendrimer-encapsulated metal nanoparticles and their applications to catalysis. These materials are prepared by sequestering metal ions within dendrimers followed by chemical reduction to yield the corresponding zerovalent metal nanoparticle. The size of such particles depends on the number of metal ions initially loaded into the dendrimer. Intradendrimer hydrogenation and carbon−carbon coupling reactions in water, organic solvents, biphasic fluorous/organic solvents, and supercritical CO2 are also described.

http://rcrooks.cm.utexas.edu/research/resources/Publications/rmc113.pdf

Dendrimer-Encapsulated Metal Nanoparticles: Synthesis, Characterization, and Applications to Catalysis

Dynamic covalent chemistry relates to chemical reactions carried out reversibly under conditions of equilibrium control. The reversible nature of the reactions introduces the prospects of "error checking" and "proof-reading" into synthetic processes where dynamic covalent chemistry operates. Since the formation of products occurs under thermodynamic control, product distributions depend only on the relative stabilities of the final products. In kinetically controlled reactions, however, it is the free energy differences between the transition states leading to the products that determines their relative proportions. Supramolecular chemistry has had a huge impact on synthesis at two levels: one is noncovalent synthesis, or strict self-assembly, and the other is supramolecular assistance to molecular synthesis, also referred to as self-assembly followed by covalent modification. Noncovalent synthesis has given us access to finite supermolecules and infinite supramolecular arrays. Supramolecular assistance to covalent synthesis has been exploited in the construction of more-complex systems, such as interlocked molecular compounds (for example, catenanes and rotaxanes) as well as container molecules (molecular capsules). The appealing prospect of also synthesizing these types of compounds with complex molecular architectures using reversible covalent bond forming chemistry has led to the development of dynamic covalent chemistry. Historically, dynamic covalent chemistry has played a central role in the development of conformational analysis by opening up the possibility to be able to equilibrate configurational isomers, sometimes with base (for example, esters) and sometimes with acid (for example, acetals). These stereochemical "balancing acts" revealed another major advantage that dynamic covalent chemistry offers the chemist, which is not so easily accessible in the kinetically controlled regime: the ability to re-adjust the product distribution of a reaction, even once the initial products have been formed, by changing the reaction's environment (for example, concentration, temperature, presence or absence of a template). This highly transparent, yet tremendously subtle, characteristic of dynamic covalent chemistry has led to key discoveries in polymer chemistry. In this review, some recent examples where dynamic covalent chemistry has been demonstrated are shown to emphasise the basic concepts of this area of science.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/1521-3773%2820020503%2941%3A9%3C1460%3A%3AAID-ANIE11111460%3E3.0.CO%3B2-N

Dynamic covalent chemistry.

Dendrimers in Supramolecular Chemistry: From Molecular Recognition to Self-Assembly.

Hydrogen bond-mediated self-assembly is a powerful strategy for generating large structures from smaller subunits. The synthesis of molecules containing two isophthalic acid units covalently attached to a rigid aromatic spacer is described. By normal pairing of carboxylic acids into hydrogen-bonded dimers, these molecules self-assemble in organic solvents to form either a series of linear aggregates or a cyclic hexamer. These molecules were linked to the core of a family of polyether dendrimers, which caused the hexamer to be formed preferentially. The stability of the hexamer depended on the generation number of the dendrimer. The largest of these hydrogen-bonded macromolecular assemblies is roughly disk-shaped with a 9-nanometer diameter and a 2-nanometer thickness. Its size and molecular mass (34,000 daltons) are comparable to that of small proteins.

https://science.sciencemag.org/content/sci/271/5252/1095.full.pdf

Self-Assembling Dendrimers

Dendrimers are polymers that radiate out from a central core, with the number of branch points on a given arm increasing exponentially from the core to the periphery. 1 Because of their novel properties, dendrimers have found many uses, including as unimolecular micelles, 2 novel amphiphiles, 3 complexation agents, 4 and MRI contrast agents. 5 These and other applications will benefit from more efficient methods of dendrimer preparation because the iterative synthetic approaches to even small dendrons are multistep. In particular, both the divergent approach developed by Tomalia 6 and Newkome 7 and the convergent method of Fre ́chet8 minimally require a deprotection or activation step in addition to the coupling step that adds each new generation. Several successful attempts to shorten these synthetic sequences were reported; 9-11 however, these approaches still require (de)protection or activation chemistry. Several years ago, Baranay and Merrifield 12 defined an orthogonal system as “a set of completely independent classes of protection groups, such that each class can be removed in any order and in the presence of all other classes.” Orthogonal protecting group strategies have found widespread use in peptide chemistry, and recently Ogawa 13 used two independent (orthogonal) glycosylation reactions to accelerate the synthesis of oligosaccharides. We now describe a rapid synthesis of dendrimers using an orthogonal coupling strategy wherein each synthetic step adds a generation to the existing dendrimer. 14

Rapid synthesis of dendrimers by an orthogonal coupling strategy

Supramolecular polymer chemistry: design, synthesis, characterization, and kinetics, thermodynamics, and fidelity of formation of self-assembled dendrimers

Fanwen Zeng

Papers

Dendrimers in Supramolecular Chemistry: From Molecular Recognition to Self-Assembly.

Self-Assembling Dendrimers

Rapid synthesis of dendrimers by an orthogonal coupling strategy

Supramolecular polymer chemistry: design, synthesis, characterization, and kinetics, thermodynamics, and fidelity of formation of self-assembled dendrimers

Dendrimers with anthyridine-based hydrogen-bonding units at their cores: Synthesis, complexation and self-assembly studies