Unraveling the Intertwining Factors Underlying the Assembly of High-Nuclearity Heterometallic Clusters.

Two closely related yet distinctly different cationic clusters, [Dy52Ni44(HEIDA)36(OH)138(OAc)24(H2O)30]10+ (1) and [Dy112Ni76(HEIDA)44(EIDA)24(IDA)4(OH)268(OAc)48(H2O)44]4+ (2) (HEIDA=N-(2-hydroxyethyl)iminodiacetate), each featuring a multi-shell core of Platonic and Archimedean polyhedra, were obtained. Depending on the specific conditions used for the co-hydrolysis of Dy3+ and Ni2+, the product can be crystallized out as one particular type of cluster or as a mixture of 1 and 2. How the reaction process was affected by the amount of hydrolysis-facilitating base and/or by the reaction temperature and duration was investigated. It has been found that a reaction at a high temperature and/or for an extended period favors the formation of the compact and thermodynamically more stable 1, while a brief reaction with a large amount of the base is good for the kinetic product 2. By tuning these intertwining conditions, the reaction can be regulated toward a particular product.

Understanding the competing pathways leading to hydropyrene and isoelisabethatriene.

Terpene synthases are responsible for the biosynthesis of terpenes, the largest family of natural products. Hydropyrene synthase generates hydropyrene and hydropyrenol as its main products along with two byproducts, isoelisabethatrienes A and B. Fascinatingly, a single active site mutation (M75L) diverts the product distribution towards isoelisabethatrienes A and B. In the current work, we study the competing pathways leading to these products using quantum chemical calculations in the gas phase. We show that there is a great thermodynamic preference for hydropyrene and hydropyrenol formation, and hence most likely in the synthesis of the isoelisabethatriene products kinetic control is at play.

High-Yield Formation of Graphdiyne Macrocycles through On-Surface Assembling and Coupling Reaction.

Rationally designed halogenated hydrocarbons are widely used building blocks to fabricate covalent-bonded carbon nanostructures on surfaces through a reaction pathway involving generation and dissociation of organometallic intermediates and irreversible covalent bond formation. Here, we provide a comprehensive picture of the on-surface-assisted homocoupling reaction of 1,3-bis(2-bromoethynyl)benzene on Au(111), aiming for the synthesis of graphdiyne nanostructures. Submolecular resolution scanning tunneling microscopy and noncontact atomic force microscopy observations identify the organometallic intermediates and their self-assemblies formed in the dehalogenation process. The demetallization of the organometallic intermediates at increased temperatures produces butadiyne moieties that spontaneously formed two different covalent structures ( i.e., graphdiyne zigzag chains and macrocycles), whose ratio was found to depend on the initial coverage of organometallic intermediates. At the optimal condition, the stepwise demetallization and cyclization led to a high-yield production of graphdiyne macrocycles up to 95%. Statistical analysis and theoretical calculations suggested that the favored formation of macrocycles resulted from the complex interplay between thermodynamic and kinetic processes involving the organometallic bonded intermediates and the covalently bonded butadiyne moieties.