Rhenium(i) based irregular pentagonal-shaped metallacavitands

Abstract

Neutral ditopic flexible N-donor ligands (Ln = bis(4-(naphtho[2,3-d]imidazol-1-ylmethyl)phenyl)methane, L1 bis(4-(benzimidazol-1-ylmethyl)phenyl)methane, L2 or bis(4-(2-nonylbenzimidazol-1-ylmethyl)phenyl)methane, L3) possessing a bis(4-methylphenyl)methane spacer with two imidazolyl donor units were designed and synthesized. The ligands were utilized to develop metallacavitands analogous to irregular pentagonal-shaped metallacavitands with larger cavities. The metallacavitands 1-4 were assembled from Re2(CO)10, a rigid bis-chelating donor (1,4-dihydroxy-9,10-anthraquinone or chloranilic acid) and Lnvia a solvothermal approach. The ligands and the metallacavitands were characterized by analytical and spectroscopic methods. The molecular structures of 1 and 4 were further confirmed by single crystal X-ray diffraction analysis which revealed that a toluene molecule resides in the hydrophobic cavity. Ln and 1-4 are emissive in DMSO at room temperature. The internal cavity of the metallacavitand acts as a host for aromatic guest molecules. The host-guest interaction properties of 1 with anthracene, naphthalene, nitrobenzene, 2-nitrotoluene, 4-nitrotoluene and 2,4-dinitrotoluene were studied by an emission spectroscopic method.

Tuning the Size and Geometry of Pd(II)-Based Metallacalixarenes by Varying the N-Containing Ligands: Synthesis, Structure, and Sensing Properties

“…Calixarene-shaped molecules constructed with phenol as building blocks and methylene as linkers have attracted persistent interest owing to their peculiar structural features and wide practical applications. − Compared with calixarenes, both organic units and inorganic metal centers included calixarene-like metallacalixarenes are under-explored. ,− By employing coordination interactions between the inorganic metal centers and organic compounds as ligands via metal-directed self-assembly, metallacalixarenes exhibit diverse structural potential as well as magnetic, gas adsorptive/separative, electrochemical, and catalytic functionality. ,− It is noteworthy that the metallacalixarenes are capable of encapsulating metal cations, inorganic anions, or neutral molecules because of their calixarene-shaped cavities, ,− which is attracting growing interest from chemists and material scientists. − …”

The Quest for Large Group 13 Metallacalixarenes Based on Benzymidazolyl Ligands and Al and Ga Alkyls

“…Metallacalix[n]arenes or metallocavitands with cavities larger than n=4 are rather uncommon but highly desirable to count because their larger cavities could be potentially more flexible as is the case with calix[n]arenes and metallocalix[n]arenes with n>4 [20] to tune up substrate selectivity [2] . Examples include a pentagonal‐shaped metallocavitand assembled with a Re(CO) 3 moiety, a rigid bis‐chelating 1,4‐dihydroxy‐9,10‐anthraquinone or chloroanilinic acid donor, and a flexible ditopic N‐donor ligand, represented in Figure 1e; [10a] and a hexanuclear Pt(II)/Pd(II) metallacalixarene derived from cytosine which was mixed with the tetranuclear species in a 1 : 3 ratio [21] . Herein, on the search of large aluma‐ and gallametallacalix[n]arenes, we disclose investigations on derivatives with bromide or ethyl groups at the 2‐position of bzim ditopic ligands with the hypothesis that larger substituents than H or Me at this position may boost the formation of larger rings and therefore cavities.…”

“… Graphic representation of metallacalixarenes. a) Examples of germa‐ and stannacalixarenes with Ge or Sn instead of methylene bridges, [7b] b) Uracil‐ or cytosine‐based metallacalix[4]arene with mixed Pd II , and Pt II centers, [8a] c) Bowl‐shaped [Cu 4 (pprd) 4 (C 2 H 4 ) 4 ](PF 6 ) 4 ; [9] d) General formula of benzimidazole‐based aluma‐ and gallacalixarenes, [18] and e) Re‐based irregular pentagonal metallacavitand [{(CO) 3 Re(μ‐dhaq)Re(CO) 3 }μ‐L 1 )], H 2 dhaq=1,4‐dihydroxy‐9,10‐anthraquinone, L 1 =bis(4‐(benzimidazol‐1‐ylmethyl)phenyl)methane [10a] …”

Heterobimetallic (FeII/PtII)-Based Supramolecular Coordination Complexes Using 1,1′-Ferrocene Dicarboxylate: Self-Assembly and Interaction with Carbon Dots

“…In recent years, the phrase “supramolecular coordination complex (SCC)” has been coined as a general term by Stang to describe discrete, cyclic coordination complexes assembled using predesigned starting materials . In the realm of SCCs, the use of flexible ligands is quite interesting as well as challenging. , This is because unlike rigid tectons that yield architectures of predefined dimensions flexible tectons are less predictable as far as the shape and size of the self-assembled product is concerned . 1,1′-Difunctionalized ferrocenes are examples of flexible donor ligands that have been used in the design of SCCs.…”