This critical review presents a comprehensive study of transition-metal carboxylate clusters which may serve as secondary building units (SBUs) towards construction and synthesis of metal–organic frameworks (MOFs). We describe the geometries of 131 SBUs, their connectivity and composition. This contribution presents a comprehensive list of the wide variety of transition-metal carboxylate clusters which may serve as secondary building units (SBUs) in the construction and synthesis of metal–organic frameworks. The SBUs discussed here were obtained from a search of molecules and extended structures archived in the Cambridge Structure Database (CSD, version 5.28, January 2007) which included only crystals containing metal carboxylate linkages (241 references).

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Secondary building units, nets and bonding in the chemistry of metal–organic frameworks

Synthetic organic chemists enjoy the luxury of having a large collection of reliable reactions at their disposal for preparing small molecules, mesoscopic structures, and polymers. Coordination chemists, on the other hand, are faced with the fact that transition metal chemistry, when normalized for the number of transition metals, has relatively few high-yielding reactions, when compared to the chemistry of carbon, for preparing even small molecule structures. This lack of control is manifested, in large part, in the weak metal-ligand interactions found in coordination complexes as compared with the strong covalent bonds in organic compounds. Weak bonding often translates into many reaction pathways that are not substantially different from an energetic point of view, and therefore, results in poor selectivity. As a result, many coordination chemists in recent years have come to the realization that it may be easier and more productive to develop straightforward and reliable routes to mesoscopic supramolecular structures by capitalizing on the modest collection of high-yielding reactions in coordination chemistry, the directional bonding afforded by metal centers, and strategies aimed at taking advantage of the weak metal bonds found in coordination complexes. Three emerging synthetic strategies, the symmetry-interaction, directional-bonding, and weak-link synthetic approaches, all use metal centers as structural building blocks to rationally assemble molecular components into supramolecular metallocyclophanes. These three approaches are discussed herein, and the fundamental principles underlying each as well as their capabilities are compared and contrasted.

Strategies for the Construction of Supramolecular Compounds through Coordination Chemistry

Direct cellular responses to platinum-induced DNA damage

Hydrogen bonds are like human beings in the sense that they exhibit typical grouplike behavior. As an individual they are feeble, easy to break, and sometimes hard to detect. However, when acting together they become much stronger and lean on each other. This phenomenon, which in scientific terms is called cooperativity, is based on the fact that 1+1 is more than 2. By using this principle, chemists have developed a wide variety of chemically stable structures that are based on the reversible formation of multiple hydrogen bonds. More than 20 years of fundamental studies on these phenomena have gradually developed into a new discipline within the field of organic synthesis, and is nowadays called noncovalent synthesis. This review describes noncovalent synthesis based on the reversible formation of multiple hydrogen bonds. Starting with a thorough description of what the hydrogen bond really is, it guides the reader through a variety of bimolecular and higher order assemblies and exemplifies the general principles that determine their stability. Special focus is given to reversible capsules based on hydrogen-bonding interactions that exhibit interesting encapsulation phenomena. Furthermore, the role of hydrogen-bond formation in self-replicating processes is actively discussed, and finally the review briefly summarizes the development of novel materials (nanotubes, liquid crystals, polymers, etc.) and principles (dynamic libraries) that recently have emanated from this intriguing field of research.

Noncovalent synthesis using hydrogen bonding

Infrared spectroscopic identification of species arising from reactive adsorption of carbon oxides on metal oxide surfaces

Hydroxo-bridged platinum(II) complexes. 1. Di-.mu.-hydroxo-bis[diammineplatinum(II)] nitrate, [(NH3)2Pt(OH)2Pt(NH3)2](NO3)2. Crystalline structure and vibrational spectra

Chirality in antirheumatic drugs.

Unusual platinum complexes of deprotonated 1-methylcytosine: bis(.mu.-1-methylcytosinato-N3,N4)-bis(cis-diammineplatinum(II)) dinitrate dihydrate, [(NH3)2Pt(C5H6N3O)2Pt(NH3)2](NO3)2.2H2O, and [diaquahydrogen(1+)][bis(.mu.-1-methylcytosinato-N3,N4)-bis(cis-nitrodiammineplatinum)(Pt-Pt) dinitrate, (H5O2)[(NH3)2(NO2)Pt(C5H6N3O)2Pt(NH3)2(NO2)](NO3)2

D-penicillamine: chemistry and clinical use in rheumatic disease.

Hydroxo-bridged platinum(II) complexes. 2. Crystallographic characterization and vibrational spectra of cyclo-tri-.mu.-hydroxo-tris[cis-diammineplatinum(II)]nitrate

Colin J. L. Lock

Papers

Hydroxo-bridged platinum(II) complexes. 1. Di-.mu.-hydroxo-bis[diammineplatinum(II)] nitrate, [(NH3)2Pt(OH)2Pt(NH3)2](NO3)2. Crystalline structure and vibrational spectra

Chirality in antirheumatic drugs.

D-penicillamine: chemistry and clinical use in rheumatic disease.

Hydroxo-bridged platinum(II) complexes. 2. Crystallographic characterization and vibrational spectra of cyclo-tri-.mu.-hydroxo-tris[cis-diammineplatinum(II)]nitrate