Synthesis and Characterization of Aminoquinonato Bridged Re(I)‐Based Amide Functionalized Dinuclear Metallastirrups and Tetranuclear Lemniscate Metallacycles

Abstract

Herein, we describe a multicomponent self‐assembly approach that has the prospect of furnishing functionalized di‐ and tetranuclear metallacyclic architectures with a very less level of constitutional control using semi‐rigid ligands. The methodology relies on the coordination preference of the metal and the directionality of the ligands. Self‐assembly of Re2(CO)10, aminoquinone ligands (H2L=2,5‐bis(n‐butylamino)‐1,4‐benzoquinone (bbbq), 2,5‐bis(n‐octylamino)‐1,4‐benzoquinone (bobq) and 2,5‐bis(phenethylamino)‐1,4‐benzoquinone (bpbq)) and ditopic pyridyl ligands (N‐L′‐N=bis(4‐pyridinecarboxamide)‐1,2‐ethane (bpce), N,N′‐(1,2‐phenylene)diisonicotinamide (pdia) and N,N′‐bis(4‐pyridylformamide)‐1,4‐benzene (bpfb)) in equimolar ratio afforded amide functionalized metallacyclophanes of 1–9 (Scheme ). Compounds 1–9 have been characterized by elemental analysis, IR, NMR, UV/Vis absorption and ESI‐mass spectroscopic techniques. Molecular structures of 1, 3 and 7 were ascertained by single‐crystal X‐ray diffraction methods.

Rhenium–Pyrazolyl-Based Figure-Eight- and Z-Shaped Metallocycles: Self-Assembly, Solid-State Structures, Dynamic Properties in Solution, and Competitive Ligand-Induced Supramolecular Transformations into Rhenium-Pyridyl/-Benzimidazolyl/-Phosphine-Based Metallocycles/Acyclic Complexes

“…The design and synthesis of metallocycles such as cages, helicates, and simple-to-complex topological architectures via coordination-driven self-assembly have been gaining significant attention owing to their potential applications in materials and medicinal fields. − Further, new aesthetically appealing molecular architectures including intricate topological metallocyclic architectures such as metallo-links (a series of interlocked metallocyclic rings where at least one ring has to be broken to separate them) and metallo-knots similar to those found in nature can be prepared using the self-assembly. − Among various topologies, “figure-eight” architecture is one of the elegant self-assembled structures, which is found in natural systems such as Lissoclinamide 7, the recombinant structure of circular DNA and marine alkaloid. , However, very few examples of “figure-eight”-shaped metallocycles are known until now. − The design and synthesis of “figure-eight”-shaped metallocycles and other metallocyclic architectures using various metal precursors and organic building units are important in the development of the field, which might yield molecules having various potential applications in the near future. Among the few metal ion-based coordination-driven approaches, the fac -[Re­(CO) 3 ] core-based self-assembly method is one of the methods to construct neutral homoleptic and heteroleptic metallocycles, which have potential applications in the field of host–guest encapsulation, catalysis, selective reactivity, sensing, and as bioactive agents. − Although a considerable number of synthetic principles for the preparation of various sizes and shapes of fac -[Re­(CO) 3 ] core-based metallocycles are currently available, synthetic approaches for preparing “figure-eight” topology, complex-knot, and complex-link-shaped metallocycles are scarce.…”

Multicomponent Self-Assembly of Diaminobenzoquinonato-Bridged Manganese(I) Metallosupramolecular Rectangles: Host–Guest Interactions, Anticancer Activity, and Visible-Light-Induced CO Releasing Studies

“…The multicomponent self-assembly of transition metal-based supramolecules could result in exciting architectures with increasing complexity and functionalities; however, the sensitivity, stability, and purity of the Mn I -based target products in the self-assembly system are tricky, challenging, and unexplored . Our research group has developed an array of fac -M­(CO) 3 (M = Re I and Mn I )-based supramolecular hosts motivated by two of their remarkable properties, namely, (i) their ability to sense and bind organic guest molecules and (ii) their ability to release CO upon activation by light and their associated cytotoxic behavior. , For the purpose of binding rigid planar π-extended guests, we have focused on rectangular metallosupramolecular hosts since shape complementarity is known to improve the binding/encapsulation efficacy. On the other hand, for the photoinduced CO releasing property, we have utilized different π-extended diaminobenzoquinone linkers between Re/Mn centers in order to shift the 3 MLCT (metal–ligand charge transfer in the triplet excited state) transition well into the visible region, which eliminates the need for UV light for photoactivation. , …”