bluuebunny/crossref_metadata_2025 huggingface dataset:
Photoinduced Electron Transfer Processes in Biological and Artificial Supramolecules
Authors: Fujitsuka Mamoru , Majima Tetsuro
Published: February 2012

In this chapter, we introduce the photoinduced electron‐transfer processes in supramolecular systems and related biological systems that display phenomena of self‐assembly, namely, photosynthesis system and DNA. Photoinduced energy and electron‐transfer processes in natural photosynthesis systems are reviewed at first on the basis of the structure and kinetic parameters. Then, artificial photosynthesis systems, which convert light energy to chemical products such as ATP and molecular oxygen or electronic current in solar cell, are introduced. In addition, molecular machines based on electron transfer, which convert light energy to machinery motions, are also discussed. Next, chemosensors for ion and molecule detection and sensing are described using selected examples. In the following part, the photoinduced electron transfer in DNA is reviewed. The oxidative and reductive electron transfers in DNA are introduced on the basis of the kinetic parameters. Finally, sensing of base sequence in DNA on the basis of the electron‐transfer process is introduced.
Molecular Logic Gates
Authors: de Silva A. Prasanna
Published: February 2012

A wide diversity of molecular structures, chemical phenomena, and mechanisms can be marshalled to produce a large range of molecular logic operations according to the Boolean blueprint. Since the blueprint has produced society‐changing semiconductor‐based information technology, we can hope that molecular logic gates can interface with the venerable information handlers of biology especially at the cellular level. In the meantime, good progress is being made in the generalization of molecular logic. Some examples of the molecular‐level implementation of single‐input logic gates such as YES and NOT are outlined. This is followed up with molecular versions of double‐input logic gates such as AND, OR, NOR, NAND, INHIBIT, and XOR. A half‐adder is discussed as a prototypical number‐processing system.
Single‐Molecule Electronics
Authors: Metzger Robert M.
Published: February 2012

Electronic devices at the single‐molecule level (<3 nm in all directions) may provide the fastest possible electronic components, whose excited states would decay by photons, while comparably sized Si‐based components must decay by phonons, and require enormous heat dissipation methods. Progress in unimolecular rectification is reviewed, with particular emphasis on the two possible ground states (Zwitterionic or quinonoid) of quinolinium tricyanoquinodimethanide, which depend crucially on intermolecular forces. Other lively issues (metal– organic interface, future three‐ and four‐probe devices) are briefly introduced.
Molecular Redox Sensors
Authors: Tucker James H. R.
Published: February 2012

This review focuses on supramolecular receptors designed for the detection of guest species in solution by virtue of their incorporation of a redox‐active group, which is able to electrochemically respond to a binding event. The redox‐active group is normally covalently attached in close proximity to the binding site in order to maximize the redox response to complexation. The sensing process makes use of voltammetric techniques, for example, cyclic voltammetry and the sensors typically target analytes that are not electrochemically active themselves. An overview of the literature is given with a description both of various redox‐active groups that have been incorporated into receptors and also the range of targets studied, including cationic, anionic, and neutral species. Recent developments are highlighted that include the development of chiral sensors and receptors that are immobilized at various surfaces, for example, as polymeric species or as self‐assembled monolayers.
Colorimetric Sensors
Authors: Maeda Hiromitsu , Anzenbacher Pavel
Published: February 2012

This chapter is devoted to colorimetric sensors and sensors that utilize changes in absorption of light in general as a signal output to provide the evidence for sensor‐analyte association. First, the photophysical processes associated with absorption of light and the molecular orbital reasons for color change are discussed. The following sections give a brief explanation of typical molecular architectures used in colorimetric sensor design as well as a typical instrumentation used in such studies. The following sections describe colorimetric sensors for cations, anions, and electroneutral molecules or zwitterions such as amino acids. Finally, alternative approaches utilizing, for example, hybrid organic‐inorganic materials, self‐signaling polymers, and materials utilizing changes in structural color output are also briefly discussed.
Luminescent Sensing
Authors: Kitchen Jonathan A. , Parkesh Raman , Veale Emma B. , Gunnlaugsson Thorfinnur
Published: February 2012

The development of luminescent sensing has been central to the field of supramolecular chemistry. Herein, we give a some insight into some of the developments that have taken place in recent times, focusing most of our effort on the discussion of luminescent sensors for cations, anions, and neutral molecules, by presenting a selected number of examples from this fast, broad, and ever expanding research field. We also demonstrate how the use of luminescent sensors has helped in the development of contrast and imaging agents, and in particular show examples of their use in cellular imaging and sensing within competitive biological environments.
Supramolecular Chemistry in Medicine
Authors: Faulkner Stephen , Kenwright Alan M.
Published: February 2012

Supramolecular chemistry lies at the very heart of medicine, and interactions between molecules play a vital role in almost all aspects of medicinal chemistry. In this chapter, we provide an overview of the current role of supramolecular chemistry in medicine and perhaps encourage others to think about a wider range of medicine‐related research in terms of supramolecular chemistry. In the process, we discuss the role of supramolecular chemistry in drug action and delivery, and describe how supramolecular interactions also play a role in assay and diagnosis.
Supramolecular Chemistry for Organic Photovoltaics
Authors: Troshin Pavel A. , Sariciftci Niyazi S.
Published: February 2012

In this chapter, we focus on the supramolecular and interface chemistry of organic semiconducting materials used to create the active layers in organic solar cells. The most important types of organic solar cells, typical photoactive materials, device architectures, and operation principles are discussed. A short overview of supramolecular assembling effects in dye sensitized organic solar cells is given. The photoelectrochemical cells based on covalently and noncovalently linked donor/acceptor molecular architectures are described. Special attention is paid to the supramolecular ordering in solar cells based on small molecules, diblock copolymers, and fullerene/polymer blends. A detailed analysis of interface effects on the anode and cathode side of the photovoltaic device is presented.
Crystal Engineering
Authors: Tiekink Edward R. T.
Published: February 2012

Crystal engineering is an emerging discipline whereby practitioners aim to arrange molecules, both organic and metalorganic, in the crystalline phase by rational design. This challenge requires the exploitation of well‐known supramolecular glues such as hydrogen bonding and coordinate bonding. These are augmented by a myriad of nominally weaker and less directional noncovalent interactions that, increasingly, are being demonstrated as important in crystal structure design. Applications in fields as diverse as pharmaceuticals, photoluminescent materials, and metalorganic frameworks for gas storage are some of the motivations for crystal engineering that draw together scientists from a wide range of disciplines. This illustrated overview summarizes factors that dictate the ways molecules aggregate in the solid state, including a description of the diverse types of noncovalent interactions and other crystal packing principles that have being identified as being important in stabilizing crystal structure. Applications of crystal engineering drawn from both the organic and metalorganic realms are discussed. These include cocrystal formation, solid‐state reactions, and metalorganic framework structures. Furthermore, the importance ofin silicostudies and data mining as they relate to crystal engineering is highlighted throughout.
Noncovalent Interactions in Crystals
Authors: Gilli Paola , Gilli Gastone
Published: February 2012

The over 500 000 structures collected in current crystallographic databases represent the greatest archive of noncovalent molecular interactions ever conceived by man. Their analysis provides an invaluable basis for understanding these interactions in the crystalline state and for transferring this knowledge to gas phase and condensed phases, such as pure liquids or solutions in polar and nonpolar solvents. This chapter is intended to review the different classes of noncovalent interactions and to supply the mathematical background for their description.

For the sake of clarity, the treatment distinguishes betweenphysicalandchemicalinteractions. Physical interactions are considered essentially independent of molecular constitution and deriving from (i)van der Waals forces(atomic repulsion/exchange and attraction/dispersion terms); (ii)electrostatic multipolar forces(mostly monopolar and dipolar terms); and (iii)hydrophobic forces, a kind of interaction that develops in crystal clathrates and water solutions. Conversely, interactions of chemical nature are strictly related to the physicochemical properties of molecules with particular concern for (iv) groups that are either Brønsted acids (proton donors, DH) or Brønsted bases (proton acceptors, :A) and may interact by formingDH⋯:A hydrogen bondsand (v) groups that are either Lewis bases (electron donors, D:) or Lewis acids (electron acceptors, :A) and may interact by formingD: → Aelectron donor–acceptor (EDA) orcharge‐transfer(CT)interactions.

Special emphasis is given to interactions that play a determinant structure‐directing role in molecular interaction and recognition phenomena, such as hydrogen and halogen bonding.
Cocrystals: Synthesis, Structure, and Applications
Authors: Aakeröy Christer B. , Chopade Prashant D.
Published: February 2012

The crystal structure of a compound, the 3D orientation and organization of molecules in a highly regular manner, ultimately determines most of the fundamental physical properties of that particular material, for example, thermal stability, hygroscopicity, conductivity, and mechanical strength. Consequently, an ability to control and change the crystalline environment of a material without altering the molecular properties would be of enormous significance to both manufacturers and consumers of solid specialty chemicals such as pharmaceuticals, pigments, energetic materials, toxins, foodstuff, and detergents.

Preparation of cocrystals—homogeneous crystalline solids composed of different molecular building blocks—offers an additional path for incorporating functional molecules, active ingredients, within a crystalline casing, but the synthetic challenges associated with supramolecular synthesis are numerous and nontrivial.

This chapter describes several strategies for the assembly of cocrystals using hydrogen bonds and halogen bonds and provides a more in‐depth examination of how the electrostatic charge on individual attempts can be used to control efficiency and selectivity of supramolecular synthesis. Finally, a few examples of applications of cocrystals in pharmaceutical sciences are discussed.
Polymorphism: Fundamentals and Applications
Authors: Aitipamula Srinivasulu , Nangia Ashwini
Published: February 2012

Polymorphism is the ability of a compound to exist in more than one crystalline modification through different arrangements of the molecules in the solid state. Polymorphism has enormous economic and practical implications because of its ability to alter the physical and chemical properties of active pharmaceutical ingredients. The identification and complete characterization of polymorphs in the early stages of drug development is a necessary step to avoid serious financial setback in drug development and manufacturing. Thanks to new techniques such as high‐throughput screening and advances in analytical methods it has become possible to explore solid‐form diversity even with a small amount of sample in a short time. This chapter attempts to provide an overview of the fundamentals of polymorphism and the factors that control the crystallization of polymorphs. The potential implications of polymorphism in the pharmaceutical industry are highlighted with some recent examples.
Mechanical Preparation of Crystalline Materials. An Oxymoron?
Authors: Braga Dario , Dichiarante Elena , Grepioni Fabrizia , Lampronti Giulio I. , Maini Lucia , Mazzeo Paolo P. , D'Agostino Simone
Published: February 2012

The thesis developed in this chapter is that reactions taking place between molecular materials (intersolid) or within a molecular material (intrasolid) can be used to produce new crystalline materials in solvent‐free conditions and often with quantitative yields. The most common approach to intersolid and, to lesser extent, intrasolid processes is based on the mechanical cogrinding of the solid reactants, which implies comminution of the reactants. The implicit consequence of this is the lack of crystals of the product suitable for single‐crystal X‐ray diffraction. The mechanical process yields a polycrystalline or amorphous product, with structure and composition that often differ from that obtained from solution crystallization.
Physico‐Chemical Aspects of Inclusion Compounds
Authors: Báthori Nikoletta B. , Nassimbeni Luigi R.
Published: February 2012

We summarize the macro properties of organic inclusion compounds in terms of their kinetics of desorption and enclathration, their thermal stability, and the selectivity that host compounds exhibit toward a given guest from a guest mixture. We note the importance of the mechanism of enantiomeric resolution and correlate the various phenomena with the structure of the inclusion compounds.
Templated [2+2] Photodimerizations in the Solid State
Authors: Elacqua Elizabeth , Laird Rebecca C. , MacGillivray Leonard R.
Published: February 2012

This chapter describes how principles of supramolecular chemistry based on the use of small‐molecule and metal‐organic templates can be used to direct intermolecular [2+2] photodimerizations in the organic solid state. The approach provides a general means to gain control of reactivity so as to provide access to molecules difficult to achieve in solution stereospecifically, in quantitative yield, and in gram amounts.
Gas Storage and Separation in Supramolecular Materials
Authors: Tian Jian , Thallapally Praveen K. , McGrail Bernard Peter
Published: February 2012

This chapter provides an overview of gas storage and separation applications using Porous Materials. Due to space constraints, we focused our discussion on Organic, Inorganic and Hybrid materials in other words metal organic frameworks.
Soft Matter Science—a Historical Overview with a Supramolecular Perspective
Authors: Smith David K.
Published: February 2012

Soft matter science is one of the most active interdisciplinary fields of research, sitting at the interface between chemistry, biology, and condensed matter physics. One of the reasons for the intense interest in soft matter systems is that they are highly dynamic and responsive to a range of different stimuli, making them of interest for a wide range of smart applications. This article provides an introductory overview of the topic of soft matter science and attempts to place it in a historical context, tracing the genesis of the field from its disparate roots in colloid science, liquid crystals, and polymer chemistry. In particular, the article demonstrates how soft matter systems relate to the area of supramolecular science, and it attempts to connect the genesis of the supramolecular approach to soft matter nanoscience with the disparate areas of research that underpin it. In this way, it is possible to achieve a holistic approach to the development of soft matter systems with applications in nanoscience and technology.
Supramolecular Dendrimer Chemistry
Authors: Soler Monica , Newkome George R.
Published: February 2012

The field of dendrimers and dendrons has grown over the past one score and five years in both academic and industrial areas, becoming an interdisciplinary field between chemistry, physics, and medicine, leading specifically to nanoscience, and inspiring chemists to develop new materials and to explore their imbedded technological applications. Dendrimers are well‐defined highly branched three‐dimensional macromolecules with nanoscale scope and globular hollow structures with increased generation. One reason for their rapid growth is due to their precise structures and prearranged physical and functional properties such as the ability to encapsulate guests as well as polyfunctional surface constructs, control over structural unit positioning during synthesis, solubility, ease of construction, and limitless structural modifications. Owing to their macromolecular distinctiveness, this short overview will introduce the general properties of dendrimers and dendrons, with specific focus on their structure and host–guest chemistry where molecular recognition may occur within the interior of the dendrimer or at its surface, as well as consider their interactions between themselves or with other nano‐objects.
Hyperbranched Polymers in Supramolecular Chemistry
Authors: Greenland Barnaby W. , Hayes Wayne
Published: February 2012

This chapter reviews notable examples of the combination of hyperbranched polymer architectures with noncovalent interactions which have afforded interesting materials and molecular devices.
Stimuli‐Responsive and Motile Supramolecular Soft Materials
Authors: Topham Paul D. , Ryan Anthony J.
Published: February 2012

Motility is achieved by energy conversion. In nature, motility is linked to stimuli‐responsive behavior occurring at the nanometer length scale, the operation of molecular machines. Nature's molecular machines all comprise of actuator material; where an actuator is a device that converts one source of energy into another to generate a force or motion. Such stimuli‐responsive materials are often referred to assmartbecause they respond to changes in their surrounding environment. The ability of a substance to react to an external trigger is the key step in actuation. However, the fabrication of these devices relies on a set of strict design rules concerning physics at the molecular level. This chapter discusses these design rules and highlights advances in the field of smart polymers that are powered by changes in magnetic field, light, and chemical surroundings. In each case, the reader will be guided through the basic operation (i.e., how they work), common manufacturing strategies, characterization procedures, and potential applications.
Self‐Assembly of Facial Amphiphiles in Water
Authors: Boekhoven Job , van Rijn Patrick , van Esch Jan H.
Published: February 2012

In this article, an overview is given concerning facial amphiphiles in nature, bio‐, and supramolecular chemistry. In facial amphiphiles, the hydrophilic and hydrophobic parts are separated by the longitudinal axis of molecule, this in contrast to head‐tail amphiphiles in which the hydrophilic and hydrophobic groups each occupy one end of an elongated molecule. This different distribution of hydrophilic and hydrophobic groups with respect to the overall molecular shape leads to a variety of functions which are unique for facial amphiphiles, including emulsification and solubilization of hydrophobic compounds, as antibiotics and pore‐forming agents in bilayer membranes, and as membrane curvature sensing and regulating agents. In nature facial amphiphiles occur mainly as low molecular weight compounds such as the bile acids, and as a variety of peptides, alone or as part of larger proteins. Synthetic facial amphiphiles have been synthesized ranging from low molecular weight to polymers and dendrimers for the purpose of novel building blocks for supramolecular architectures and to mimic the natural functions of facial amphiphiles. In this article, we gave an overview of the self‐assembly and interfacial behavior of both natural as well as synthetic facial amphiphiles and discuss their most important biological functions and applications.
Self‐Assembly of Surfactants at Solid Surfaces
Authors: Ferrari Michele
Published: February 2012

Recent studies have shown how surfactants, well beyond their huge impact in our everyday life, have become the key tool to manipulate surface properties in order to fulfill new research and industrial requirements ranging from fluids to disperse systems management, bio and nanotechnologies naming but a few.

In this work, the author has focused on self‐assembly of surfactants at solid surfaces discussing both theoretical and simulation aspects, and conventional and more advanced experimental techniques to assess morphological, chemical, or physicochemical features of these phenomena from the nano to the macroscale.

A wide range of examples has been shown to evaluate their application potential.
Self‐Organization and Self‐Assembly in Liquid‐Crystalline Materials
Authors: Goodby John W. , Saez Isabel M. , Cowling Stephen J.
Published: February 2012

Liquid crystals comprise a number of thermodynamically stable states, which occur between the melting of a material and the formation of an amorphous liquid. Liquid crystals are the quintessential molecular materials of the modern era, being found in many types of display device, from watches and calculators to laptop computers and TVs, in high yield strength polymeric materials such as Kevlar®, and in soft materials such as soaps and detergents. Control of the self‐organizing and self‐assembling properties of liquid crystals makes these applications possible. In the following text, we describe many types of interactions at various levels of molecular complexity in the formation and stabilization of liquid crystal mesophases. The discussion ranges from covalently bound materials through to ionic‐ and charge‐transfer systems, and from molecular materials to super‐ and supramolecular systems.
Covalent Capture of Self‐Assembled Soft Materials
Authors: Gong Bing
Published: February 2012

This chapter describes the covalent capture of soft materials with examples from covalently captured liquid crystals as well as gels of small molecules and polymers. The interplay of self‐assembly and the incorporation of various covalent bonds, including irreversible and covalent reversible bonds, are discussed. The development of basic, tunable association units allowing the systematic control of molecular assembly and covalent capture is speculated.
Designing Peptide‐Based Supramolecular Biomaterials
Authors: Jayawarna Vineetha , Ulijn Rein V.
Published: February 2012

One rapidly emerging area where supramolecular chemistry can have a significant impact is in biomaterials science, and specifically in the design of cell‐contacting biomaterials. Aspects that are known to influence cell behavior at any particular time include chemical signals, mechanical properties (i.e., gel stiffness), and topographical signals related to fiber sizes and alignment. In this chapter, we provide an overview of current supramolecular chemistry strategies in the design of cell scaffolds based on peptides and their derivatives. The approaches discussed include those inspired by secondary or quaternary structures (α‐helix, β‐sheet, collagen triple helix) found in natural proteins as well as synthetic sequences such as aromatic and aliphatic peptide amphiphiles. We then discuss how supramolecular fibers based on peptides can be designed to control and direct (stem) cell behavior by engineering stiffness and chemical presentation of bioactive ligands.
Supramolecular Organocatalysis
Authors: Woods Philip A. , Smith Andrew D.
Published: February 2012

The use of small organic molecules as catalysts for a wide range of asymmetric transformations has blossomed into a remarkably diverse field under the global heading of organocatalysis. A key central theme of organocatalysis is molecular recognition, which relies on established patterns of reactivity and interactions common to traditional “supramolecular chemistry” such as hydrogen bonding, π‐stacking, cation–π, ionic, and hydrophobic interactions. This chapter presents selected highlights of these approaches in organocatalysis and also compares the way in which Nature's enzymatic supramolecular catalysts have inspired synthetic strategies and modes of action of many organocatalytic approaches to chemical reactivity.
Reactions in Solid‐State Inclusion Compounds
Authors: Harris Kenneth D.M. , Palmer Benjamin A. , Edwards‐Gau Gregory R.
Published: February 2012

This chapter focuses on chemical reactions occurring within solid organic inclusion compounds, encompassing a broad range of inclusion compounds and a wide variety of different reaction types, including reactions of the guest molecules (such as dimerization, polymerization, cyclization, isomerization, and decomposition), reactions involving the host molecules, and guest exchange processes. In many cases, chemical transformations of guest molecules confined within solid host structures proceed with a high degree of selectivity toward a single product, and often with a high degree of stereoselectivity and/or enantioselectivity, as a consequence of the geometrical constraints imposed on the reacting molecules by the host structure. For this reason, the products obtained from such reactions are often significantly different from those obtained from the corresponding reactions in the solution state or in the “pure” crystalline phase of the guest molecules. Through the examples highlighted in this chapter, general issues relating to reactions in solid organic inclusion compounds are rationalized and discussed.
Functional Polymers
Authors: Chappell David , Greenland Barnaby W. , Hayes Wayne
Published: February 2012

This chapter outlines key developments of the combination of key supramolecular principles and polymer chemistry, notably in the realization of novel catalyst systems. Novel catalysts have been produced that offer reactivity under conditions that more traditional hetero‐ or homogeneous catalysts do not tolerate. In particular, molecularly imprinted polymer networks have been used successfully and notable examples are described in this chapter. In addition to cross‐linked polymer networks, the combination of hyperbranched polymer architectures with molecular recognition has also afforded novel catalyst systems, and recent developments in this area are outlined. Finally, the application of sonochemistry to self‐assembled latent catalysts is reviewed.
Nucleic Acid Mimetics
Authors: Coppock Matthew B. , Williams Mary Elizabeth
Published: February 2012

The naturally occurring nucleic acids have the ability to selectively recognize complementary partners, and by self‐assembly create supramolecular structures capable of storage of genetic information. Chemists are interested in mimicking the makeup and properties of nucleic acids to aid in the understanding of the natural systems, and to create functional nanomaterials for a broad range of potential applications. Nucleobase analogs, including fluorescent, hydrophobic, and inorganic bases, have been successfully incorporated into modified DNA and RNA strands. Analogs of the sugar‐phosphate backbone have been constructed to increase the strength of binding between strands, and to create alternative scaffolds for both natural and synthetic nucleobases. Synthetic analogs with a combination of nucleobase and backbone mimics provide routes toward materials with tuned physical properties geared toward specific functions. This review first describes the properties of nucleic acids that serve as models for creation of synthetic analogs before presenting recent research in each of these categories of mimics.
Supramolecular Approaches to the Study of Glycobiology
Authors: Lindhorst Thisbe K. , Kubik Stefan
Published: February 2012

Every mammalian cell is surrounded by carbohydrate conjugates forming a nano‐dimensioned layer termed “glycocalyx,” a name derived from the Greek words “glykos” for “sugar” and “kalyx” for “coat.” A cell's glycocalyx might expand to a width of 100 nanometers and more, with glycoconjugate structures of vast complexity projecting from the cell surface into an aqueous environment. Lectins are able to probe this environment by selectively binding to certain carbohydrate epitopes, and the concert of the corresponding recognition events is essential in cell‐cell communication. Because of the extremely high constitutional complexity of the glycocalyx and the sensitivity of its supramolecular characteristics to, for example, the presence of ions and many other entities, it has been difficult to unravel the secrets of glycobiology, in particular how carbohydrate‐carbohydrate and carbohydrate‐protein interactions are governed and fine‐tuned. Nevertheless, a number of important aspects of carbohydrate recognition have been identified, such as critical factors for carbohydrate complexation in water, the importance of multivalency in carbohydrate‐protein interactions, and the potential of the biosynthetic machinery that makes and delivers complex glycoconjugates. In this chapter, current knowledge about how Nature achieves carbohydrate recognition is summarized. On this basis, different approaches are presented, most of which are firmly rooted in supramolecular chemistry, that aim at elucidating the molecular basis of glycobiology. These approaches comprise the development of low‐molecular weight mimics for lectins, so‐called synthetic carbohydrate receptors, on the one hand and of multivalent and highly complex glycomimetics on the other.
Porphyrinoids: Highly Versatile, Redox‐Active Scaffolds for Supramolecular Design and Biomimetic Applications
Authors: Hill Jonathan P. , D'Souza Francis , Ariga Katsuhiko
Published: February 2012

Porphyrinoids are a growing class of oligopyrrole macrocycles that have structural and physical properties additional to those of the traditional tetrapyrrolic porphyrin macrocycles. In this chapter, after an initial description of how the porphyrins have been adapted for self‐assembly and supramolecular synthesis, we describe several aspects of porphyrinoid supramolecular systems, finally focusing on the use of an oxoporphyrinogen core as a scaffold for assembling complex oligochromophoric manifolds by using a combination of synthetic and coordination chemistries. An important feature of porphyrinoids is their increasing amenability to core functionalization, unlike the porphyrins in which peripheral derivatization has been the usual method for augmentation. Core functionalization introduces different molecular morphological possibilities for the porphyrinoids complementary to those available for the porphyrins. In fact, porphyrins and porphyrinoids can be agglomerated in supramolecular assemblies to exploit the functional and synthetic properties of both sets of compounds.
The Role of Supramolecular Chemistry in Responsive Vectors for Gene Delivery
Authors: LaManna Caroline M. , Grinstaff Mark W.
Published: February 2012

The investigation of the self‐assembly between nucleic acids and cationic molecules, such as lipids, polymers, or dendrimers, has guided and will continue to guide the development of nonviral vectors for gene delivery. By engineering these types of supramolecular complexes to facilitate the transport, protection, and release of DNA, scientists are working to overcome the barriers that have limited transfection efficiencies. Understanding the self‐assembly of cationic lipids into liposomes or micelles, as well as studying the structure of their resulting complexes with DNA, is key to enhancing gene delivery research. This chapter discusses cationic lipid–DNA supramolecular structures, their role in gene transfection, and the synthesis and evaluation of new responsive cationic lipids which aim to control both the complexation and release of DNA.
Supramolecular Chemistry in
In Vitro
Biosensors
Authors: Sun Jing , Cai Min , Lavigne John J.
Published: February 2012

Supramolecular chemistry has greatly impacted the development of biosensors for use
in vitro
. On the one hand, supramolecular materials can be used as the recognition elements or transducers in these biosensors. On the other hand, the supramolecular interactions between a host and a guest are fundamental in defining the recognition, and can be utilized to develop new sensing mechanisms or improve sensor performance. This chapter focuses on sensing motifs and sensing platforms used
in vitro
for the detection of biologically relevant targets. The highlighted biosensors are based on small molecules, polymers, and biological molecule‐nanomaterial hybrids. Detection methods presented herein primarily focus on optical, electrochemical, or mass‐sensitive modes.
Supramolecular Chemistry in Biological ImagingIn Vivo
Authors: Schultz‐Sikma Elise A. , Meade Thomas J.
Published: February 2012

Biological imaging techniques, including magnetic resonance, optical, nuclear, and ultrasound, can be valuable tools for noninvasively studying biochemical processes at the molecular level. This branch of imaging is referred to as molecular imaging. A main challenge in the field ofin vivomolecular imaging is that existing probes limit clinical applications because of their inadequate sensitivity, specificity, and targeting efficiency. Supramolecular chemistry may provide a viable solution to some of these issues. Supramolecular chemical processes involve molecular components assembled into a single, large entity via noncovalent intermolecular forces. The supramolecular concepts of host–guest interaction and self‐assembly have been widely used in the development of more specialized imaging probes forin vivoimaging. This chapter discusses how supramolecular chemistry has been used to design contrast agents with improved signal amplification and specificity for each of the different imaging modalities. Particular attention is focused on magnetic resonance imaging (MRI). Multimodal probes that have benefited from supramolecular chemistry are discussed.
Supramolecular Approaches for Inhibition of Protein–Protein and Protein–
DNA
Interactions
Authors: Battle Cooper H. , Jayawickramarajah Janarthanan
Published: February 2012

The disruption of protein–protein and protein–DNA interactions is increasingly being realized as important avenues for therapeutic intervention. Unlike the successes observed in the more mature field of small molecule derived active site antagonists, however, the sequestration of the sizeable, solvent exposed, and largely featureless protein surfaces remains a significant challenge. This chapter will provide a detailed account of the types of novel inhibitors being developed that address this challenge, with special emphasis given to supramolecular approaches. Indeed, while still in its infancy, the field of aqueous supramolecular chemistry has made great strides in the development of both covalent and self‐assembled multivalent scaffolds for use in protein surface binding. While the former can provide rigid covalent scaffolds tailored for multivalent binding, the latter has the added benefit of being dynamic and thereby can rapidly lead to protein binders that allow for template‐driven elucidation, are stimuli‐responsive, and able to project heteromeric recognition elements. Taken together, these properties give supramolecular inhibitors the potential for exciting future applications in the disruption of protein interactions.
Supramolecular Systems for Tissue Engineering
Authors: Andukuri Adinarayana , Vines Jeremy B. , Anderson Joel M. , Jun Ho‐Wook
Published: February 2012

Tissue engineering is a combination of engineering, material methods, and life sciences. One of the major challenges of developing tissues is to create a balance between biological and structural entities. Supramolecular systems, more specifically peptide‐based systems, provide a bottom‐up self‐assembling structure that resembles the native hierarchical organization of tissues. This chapter discusses in detail the use of certain supramolecular systems to aid in the engineering of different tissues, namely cardiovascular tissues, bone, dental, pancreas, neural, liver, and cartilage. Detailed examples are provided for each tissue system to show the potential of peptide‐based supramolecular systems in aiding and developing the field of tissue engineering.
Chemical Biology Using Fluorinated Building Blocks
Authors: Zamora Cristina Y. , Dafik Laila , Kumar Krishna
Published: February 2012

There is a long and rich history of the use of fluorine‐containing molecules to modulate biological function. In recent years, incorporation of fluorine atoms into biomolecular assemblies has resulted in unprecedented control of structure and function. The electronegativity of fluorine has helped unveil the physical basis for the stability of collagen; incorporation of trifluoromethyl groups into peptides and proteins has resulted in hyperstable ensembles and enabled the control of oligomer formation in the nonpolar context of biological membranes. Further, fluorinated lipids segregate from hydrocarbon lipids with identical headgroups in bilayers and serve as better vehicles for transporting macromolecular cargo into living cells. Some select systems are highlighted here and the important role of fluorinated biomolecules is discussed.
Advances in Supramolecular Chemistry of Carbon Nanotubes
Authors: Kotchey Gregg P. , Star Alexander
Published: February 2012

In this chapter, the supramolecular chemistry of carbon nanotubes (CNTs) is examined. CNTs are classified as one‐dimensional allotropes of carbon that are endowed with unique physical/mechanical, electronic, and spectral properties. These properties make CNTs attractive for various applications. To be employed for these uses, CNTs must be functionalized, which can occur by either covalent or noncovalent means. During covalent modification, the sidewalls or the end groups are subject to functionalization; the primary problem with this approach, however, is that the physical properties of the nanotube are impaired. In order to chemically modify CNTs while preserving their physical properties, noncovalent functionalization of CNTs needs to be implemented. Examples of supramolecular chemistry of CNTs include: (i) π–π stacking of aromatic compounds to the walls of CNTs, (ii) dispersing CNTs with surfactants, and (iii) polymer wrapping around a CNT. Once functionalized, CNTs can be employed in applications including supramolecular assembly, using CNTs as atomic force microscope (AFM) probes, biorecognition, polymer reinforcement, recognition layers for chemical and biological sensing based on conductivity and fluorescence, the separation of nanotubes, and the use of CNTs for intercellular drug delivery.
One‐Dimensional Nanostructures of Molecular Graphenes
Authors: Zhang Wei , Fukushima Takanori , Aida Takuzo
Published: February 2012

Graphene, a 2D honeycomb network of sp
2
‐hybrized carbon atoms, attracts considerable attention in many research fields because of its extraordinary mechanical and electronic properties. Despite such superb aspects originating from extended π‐conjugation, graphene is not easy to handle, process, and modify. Hence, chemists have been motivated to develop its analog that are able to avoid such problems. Hexabenzocoronene derivatives, which have been named “molecular graphene,” are one of the representatives of such structural analogues. They consist of 13 fused benzene rings and are readily available by oxidative cyclization of hexaarylbenzene derivatives. The development of this synthetic protocol has made it possible to design “soft organic graphite” by supramolecular chemistry. As expected from the π‐stacked architecture of graphite, such graphite‐like organic materials, formed by the assembly of molecular graphenes, display interesting properties such as anisotropic charge carrier transport. This chapter describes the historical background of the synthesis of molecular graphenes and highlights fabrication and properties of their one‐dimensionally assembled nanostructures with fibrous and tubular morphologies.
Nanoelectronics
Authors: McClenaghan Nathan D. , Ducrot Aurélien
Published: February 2012

Nanoelectronics concerns processing, transmitting, and storing information, as well as switching at the single‐molecule level, often by taking advantage of properties of matter that are distinctly different than those of macroscopic/bulk properties. Strategies, architectures, and materials considered are typically different than those based on “top‐down” CMOS technologies favored in microelectronics, potentially offering an alternative or hybrid technology from a “bottom‐up” approach. In the current overview, particular emphasis is paid to disruptive technologies that are based on molecular, rather than atomic, systems and cases where supramolecular materials, including biological materials, carbon‐based nanomaterials and nanotubes, coordination and conjugated polymers, and molecular machines, are employed and have already started to find application. Equally, the role of noncovalent interactions (π–π stacking, hydrogen‐bonding, electrostatic interactions) in templating, patterning, and nanolithography as well as determining device performance in organic field‐effect transistors, organic photovoltaic devices, and organic light‐emitting diodes is considered. Apparent limitations and perspectives for device development are highlighted in this chapter.
Nanolithography
Authors: Leggett Graham J.
Published: February 2012

A wide range of strategies is now available for organizing molecules at nanometer length scales. Photolithography is the paradigmatic semiconductor processing methodology. We examine the limits on its resolution, and the methods that can be used to enhance its performance. Electron beam lithography offers ultimate resolution; while it requires access to expensive and complex apparatus, it has some significant applications in molecular patterning at small length scales. Soft lithography does not offer such high resolution, but such is its versatility and simplicity that it has become an invaluable tool in supramolecular science. Nanoimprinting and colloidal lithography offer alternate approaches to the physical deposition and removal of material at high resolution. The most widely used scanning probe lithography technique to date has been dip‐pen nanolithography. A wide range of molecules may be patterned on different substrates, and parallelization is now enabling the fast patterning of large areas. Nanoshaving/nanografting represents an opposite approach, involving the selective removal of materials from monolayers. Constructive nanolithography uses a localized tip‐induced oxidation to modify the chemistry of a monolayer, enabling the construction of complex molecular films. Finally, scanning near‐field photolithography uses a near‐field probe to initiate nanometer‐scale photochemical transformations of molecular structure.
Nanotechnology: The “Top‐Down” and “Bottom‐Up” Approaches
Authors: Iqbal Parvez , Preece Jon A. , Mendes Paula M.
Published: February 2012

Nanotechnology has grown at an enormous rate for the past three decades, and recent advances in nanostructured materials and nanodevices have opened up new opportunities in a variety of applications, ranging from information and communication technology to healthcare and medicine. Herein, an overview of nanotechnology is given, describing the origins of the field, present technology, ongoing research, and future aspirations. In addition, the two possible methodologies of fabrication—the top‐down and bottom‐up approaches—are discussed, covering the merits and drawbacks of each approach. As an example of a top‐down procedure, the fabrication of electronic integrated circuits and the foreseen limitations of the procedure for further miniaturization are described. The bottom‐up approach, through self‐assembly and supramolecular chemistry, provides an exciting alternative route either combined with the top‐down approach or on its own.
Self‐Assembled Nanoparticles
Authors: O'Reilly Rachel K.
Published: February 2012

Supramolecular self‐assembly techniques have provided a versatile means by which to selectively assemble polymeric molecules into well‐defined three‐dimensional nanostructures. The stabilization and tailoring of these dynamic nanostructures can be achieved using a range of chemistries to afford functional robust nanoparticles. In this review, we highlight the current techniques and science toward the application of aqueous self‐assembly techniques for the synthesis of polymer nanostructures. There are two main aspects addressed within this review, the first being the synthesis of spherical particles (with a focus on micelles and vesicles) and second the current literature state of the art for the preparation of anisotropic particles.
Supramolecular Hybrid Nanomaterials As Prospective Sensing Platforms
Authors: Biyikal Mustafa , Hecht Mandy , Martínez‐Máñez Ramón , Rurack Knut , Sancenón Félix
Published: February 2012

Supramolecular interactions are vital processes in many chemical sensors, biochemical assays, and other analytical detection schemes. On the background of the current, rapidly developing, and constantly changing requirements for (bio)analytical techniques, the classical molecular host is increasingly overburdened to accomplish a specific analytical task with the desired selectivity and sensitivity. Instead, other signaling strategies have to be conceived that overcome the limits in signal output, dynamic range, or compound targeting, which are imminent to various traditional methods. A very promising approach is the combination of concepts of supramolecular chemistry with nanostructured or nanoscopic inorganic materials, that is, the development of hybrid sensor materials. Such hybrids often lead to improved functionality and enhanced performance, and the present chapter discusses the contributory features in relation to the major aspects, which are related to the enhanced coordination by the preorganization of binding sites, signal amplification by the preorganization on surfaces, aggregation‐mediated signaling, surface‐modification‐based signaling, the tuning of selectivity through polarity and size, and gated signaling.
Rotaxanes–Self‐Assembled Links
Authors: Ma Xiang , Tian He
Published: February 2012

Various rotaxanes continue to be a hot topic for research currently. This article mainly focuses on the construction strategies of rotaxanes. The traditional template‐directed strategies of rotaxane synthesis, including the employment of supramolecular interactions such as hydrogen bonding, hydrophobic effect, donor–acceptor π–π stacking interaction, coordination, and ionic template were reviewed, respectively. Some novel synthetic protocols, like “Click” chemistry, “threading‐followed‐by‐shrinking” and “threading‐followed‐by‐swelling” protocol, as well as self‐sorting organization, were also introduced. The synthesis of [1]rotaxanes was also illustrated.