Supramolecular Rectangles Research Articles

Synthesis, structure, CO releasing, and biological activities of new 1-D chain Mn(I)/Mn(II) visible light activated CO-releasing molecules (CORMs)

The manganese tricarbonyl complex {[Mn2(CO)6Mn(H2O)4(BPDC)2]·2H2O}n (1) (BPDC = 2,2′-bipyridyl-4,4′-dicarboxylic acid) was synthesized from the reaction of MnBr(CO)5 with 2,2′-bipyridyl-4,4′-dicarboxylic acid. Various fac-Mn(CO)3 cores based on mononuclear complexes were achieved and only a handful of the Mn(I)-based dinuclear metallastirrups or supramolecular rectangles were reported. Interestingly, our compound is the first example of a CORM with 1-D ladder-like chain and Mn(I)/Mn(II) mixed valence state. Studies show that 1 can release CO under three different wavelengths of light (Green: λ = 520–530 nm; Blue: λ = 465–470 nm; UV: λ = 365–370 nm) and CO releasing rate can be adjusted by changing the wavelength of the irradiation light. Density functional theory (DFT) calculations were conducted to analyze the effect of metal-to-ligand charge transfer (MLCT) on CO releasing behaviors. Furthermore, cellular viability assay and anti-inflammatory activities showed that 1 possessed biological compatibility but no systemic cytotoxicity, and could prevent LPS-induced secretion of TNF-α and NO in RAW264.7 cells. The results suggest that 1 may provide a therapeutic approach for inflammation.

Hydrogen bonded molecular rectangle of N,N¢-bis(3-quinolyl- methylene)diphenylethanedionedihydrazone

The title compound, N , N ¢ -bis (3-quinolylmethylene) diphenylethanedionedihydrazone ( I ) (molecular formula, C 34 H 24 N 6 ) has been synthesized by the reaction of quinoline 3-carboxaldehyde and diphenylethanedionedihydrazone in 2:1 molar ratio. The molecular structure has been characterized by room-temperature single-crystal X-ray diffraction which reveals that two quinoline moieties are disposed nearly perpendicularly around the central C-C bond giving an ‘L’ shape to the molecule. This particular geometry gives rise to the hydrogen bonded supramolecular rectangle of two self-complementary molecules. These supramolecular units are further assembled by p-p interaction.

Synthesis, crystal structure, DFT studies, and Hirshfeld surface analysis of N,N'-bis(3-quinolyl-methylene)diphenylethanedione dihydrazone

The synthesis, characterization, and theoretical studies of a novel hydrazine, N,N’-bis-(3-quinolylmethylene)diphenylethanedione dihydrazone (1) has been reported. The molecular structure has been characterized by room-temperature single-crystal X-ray diffraction which reveals that two quinoline moieties are disposed nearly perpendicularly around the central C-C bond giving a ‘L’ shape of the molecule. This particular geometry gives rise to the hydrogen-bonded supramolecular rectangle of two self-complementary molecules. These supramolecular units are further assembled by π-π interaction. The Hirshfeld surface analysis of compound 1 shows that C···C, C···H, H···H, and N···H interactions of 13.1, 9.9, 52.3, and 7.4%, respectively, which exposed that the main intermolecular interactions were H···H intermolecular interactions. Crystal data for C34H24N6: Triclinic, space group P-1 (no. 2), a = 10.885(3) Å, b = 11.134(3) Å, c = 12.870(3) Å, α = 90.122(6)°, β = 114.141(6)°, γ = 110.277(5)°, V = 1316.1(6) Å3, Z = 2, T = 100(2) K, μ(MoKα) = 0.080 mm-1, Dcalc = 1.304 g/cm3, 7309 reflections measured (3.518° ≤ 2Θ ≤ 39.276°), 2318 unique (Rint = 0.0527, Rsigma = 0.0565) which were used in all calculations. The final R1 was 0.0416 (I > 2σ(I)) and wR2 was 0.1074 (all data).

Supramolecular rectangles through directional chalcogen bonding.

Supramolecular rectangles are built from the 2+2 chalcogen bonding-based (ChB) association of 1,8-bis(telluromethylethynyl)-anthracene (BTMEA) and ditopic Lewis bases such as 4,4'-bipyridyl-ethane and analogs, demonstrating the strength and directionality of the ChB interaction in such alkynyl-telluroalkyl derivatives.

Supramolecular rectangles and ladders constructed from Ni(II), Cu(II) and Zn(II) mononuclear complexes with bicompartmental ligands and 4-aminopyridine as tectons

Abstract By reacting [MII(valpn)] or [MII(valdmpn)] mononuclear complexes with 4-aminopyridine in different molar ratios, five [MII(valXpn)(4-NH2-py)] and one [NiII(valdmpn)(4-NH2-py)2] complexes were obtained and structurally characterized (MII = NiII, CuII, ZnII; valpnH2 and valdmpnH2 are the Schiff bases resulted from the condensation of o-vanillin with 1,3-propylenediamine and 2,2-dimethyl-1,3-propylenediamine respectively). In the [Cu(valpn)(4-NH2-py)], [Ni(valpn)(4-NH2-py)], [Zn(valpn)(4-NH2-py)] and [Ni(valdmpn)(4-NH2-py)] complexes the metal ions are pentacoordinated with a square pyramidal geometry. The specific hydrogen bond interactions of the amino group belonging to the 4-aminopyridine with the free O2O′2 compartment of the Schiff base ligands led to various supramolecular architectures: rectangles, chains, and ladders. The spectroscopic properties of the compounds were also investigated.

A new tecton with parallel halogen-bond donors: a path to supramolecular rectangles.

A new tecton, 1,8-diiodoethynylanthracene, with two halogen-bond donor sites was synthesized and characterized. This tecton is capable of forming two parallel halogen bonds at once, which makes it a useful building block for the construction of a variety of supramolecular squares and rectangles.

Construction of molecular rectangles with titanium-oxo clusters and rigid aromatic carboxylate ligands.

Four rectangular molecular architectures have been successfully constructed using {Ti5O7} clusters as inorganic vertical edges and bridging aromatic carboxylates as horizontal edges. The introduced organic ligands show a strong influence on the light absorption behaviors of the obtained hybrid complexes.

Synthesis, Structural Characterization, and Host–Guest Studies of Aminoquinonato-Bridged Re(I) Supramolecular Rectangles

Aminoquinonato bridged Re(I)-based metallarectangles have been constructed via an orthogonal bonding approach. Self-assembly of Re2(CO)10 and aminoquinone ligands in the presence of ditopic linear pyridyl ligands has resulted in the formation of metallarectangles of the general formula [{(CO)3Re(μ-η(4)-L)Re(CO)3}2(μ-N-L'-N)2] (1-4), wherein 1, L = 2,5-bis(n-butylamino)-1,4-benzoquinonato (bbbq) and N-L'-N = 4,4'-bipyridine (bpy); 2, L = 2,5-bis(phenethylamino)-1,4-benzoquinonato (bpbq) and N-L'-N = 4,4'-bipyridine; 3, L = 2,5-bis(n-butylamino)-1,4-benzoquinonato (bbbq) and N-L'-N = trans-1,2-bis(4-pyridyl)ethylene (bpe) and 4, L = 2,5-bis(phenethylamino)-1,4-benzoquinonato (bpbq) and N-L'-N = trans-1,2-bis(4-pyridyl)ethylene (bpe). Metallarectangles 1-4 have been characterized by elemental analysis, IR, NMR, and UV-vis absorption spectroscopic techniques. The molecular structures of 1 and 4 were determined by single-crystal X-ray diffraction methods. The molecular recognition capability of 1 and 3 with pyrene and triphenylene has been investigated using UV-vis absorption and emission spectroscopic techniques. The formation of host-guest complex has been further corroborated by the single-crystal X-ray structural evidence of carceplex system (3⊃pyrene)·(DMF).

Self-assembly of Thiolato-Bridged Manganese(I)-Based Metallarectangles: One-pot Synthesis and Structural Characterization.

A new series of thiolato-bridged manganese(I)-based supramolecular rectangles have been achieved by three-precursor self-assembly of Mn2(CO)10, diaryl disulfides (RSSR), and linear ditopic azine ligands (L) [L = pyrazine (pz), 4,4'-bipyridine (bpy), and trans-1,2-bis(4-pyridyl)ethylene (bpe)] using a one-pot synthetic strategy. Oxidative addition of RSSR (diphenyl disulfide and p-tolyl disulfide) to manganese decacarbonyl in the presence of rigid bidentate ligands (L) afforded metallarectangles of the general formula [{(CO)3Mn(μ-SR)2Mn(CO)3}2(μ-L)2] (1-6). Compounds 1-6 were characterized using elemental analyses and NMR, IR, and UV-vis absorption spectroscopic techniques. The molecular structures of metallarectangles 1, 3, and 5 were elucidated by single-crystal X-ray diffraction methods. The guest binding ability of 3 and 5 has been investigated with two aromatic guests using electronic absorption and fluorescence emission spectroscopy, and the results revealed a strong binding interaction between host-guest species.

Synthesis and Spectroscopic and Structural Characterization of Oxamidato-Bridged Rhenium(I) Supramolecular Rectangles with Ester Functionalization

Oxamidato-bridged Re(I)-based supramolecular rectangles with an ester functionality have been synthesized via an orthogonal bonding approach under solvothermal conditions. Self-assembly of Re2(CO)10 and oxamide ligands (H2L1 = N,N′-dibutyloxamide, H2L2 = N,N′-dioctyloxamide, H2L3 = N,N′-didodecyloxamide, and H2L4 = N,N′-dibenzyloxamide) with the pyridyl ligand phenyl-1,4-bis(isonicotinate) (pbin) has resulted in the formation of metallarectangles of general formula [{(CO)3Re(μ-η4-L)Re(CO)3}2(μ-pbin)2] (1–4), wherein L = N,N′-dibutyloxamidato (1), N,N′-dioctyloxamidato (2), N,N′-didodecyloxamidato (3), N,N′-dibenzyloxamidato (4) and pbin = phenyl-1,4-bis(isonicotinate). The metallarectangles have been characterized using spectroscopic techniques, and single-crystal X-ray structures have been obtained for 1 and 4. The guest binding ability of 2 has been investigated with a few aromatic amines and an amino ketone using electronic absorption and fluorescence emission spectroscopy, and the results revealed a s...

Insights About the Mechanism of the Formation of Supramolecular π‐Stacked Rectangles Based on CuI Bimetallic Complexes Bearing a Bridging Phosphane Ligand

AbstractThe variation in the ratio of the reactants in the supramolecular self‐assembly reaction of the bimetallic CuI “U‐shaped” molecular clip 1 with the 1,4‐dicyanobenzene 3 and the 1,8‐anthracene‐9,10‐carbonitrile 4 “short” ditopic ligand have allowed the observation of new “open” supramolecular assemblies 7 and 8, respectively, in addition to the previously characterized π‐stacked supramolecular rectangles 5 and 6, respectively. These new derivatives have been characterized by their solid‐state structure obtained by X‐ray diffraction on single crystals and by NMR spectroscopy in the case of derivative 7. Depending on the extent of the π system included in the core of the homoditopic linker, different behaviors are observed. In the case of derivative 7 based on the “phenyl” linker 3, a 1:1 1/3 ratio affords the open derivative in a good yield, whereas a 1:0.5 1/4 ratio allows the isolation of derivative 8 in very low yield. These results allow for a tentative analysis of the mechanism that occurs along with the supramolecular self‐assembly processes to afford π‐stacked supramolecular rectangles.

Supramolecular Architectures of Pt(II) Complexes Controlled by Hydrogen Bonds and by Guest Molecules

The synthesis, the characterization, and the X-ray structures of cis- and trans-Pt(II) complexes with α-(4-pyridyl)benzhydrol are reported. The crystal organization of several solvates is presented and compared with particular regard to the role of the hydrogen bond in the formation of the supramolecular architecture and how this is regulated by the presence of guest solvent molecules. It is shown that these networks are flexible as a response to the insertion of small molecules. trans-Complexes reproduce the “venetian blinds” pattern observed for the palladium analogs [Bacchi, A.; Bosetti, E.; Carcelli, M.; Pelagatti, P.; Rogolino, D.; Pelizzi, G.Inorg. Chem. 2005, 44, 431 and Bacchi, A.; Bosetti, E.; Carcelli, M.CrystEngComm 2005, 7, 527], while cis-complexes persistently give supramolecular rectangles assisted by the concomitant presence of OH···OH hydrogen bonds and edge-to-face interactions between aromatic rings inside the rectangles. These rectangles are packed by taking advantage of OH···Cl interactions unless the guests provide other means of satisfying the hydrogen bond donor/acceptor balance.

Aurophilicity versus Mercurophilicity: Impact of d10–d10 Metallophilic Interactions on the Structure of Metal‐Rich Supramolecular Assemblies

Treatment of U-shaped, binuclear Cu(I) complexes 1,1' (1, counterion: BF(4)(-); 1', counterion: PF(6)(-)) with metal cyanide linear linkers K[Au(CN)(2)] (3) and Hg(CN)(2) (4) lead to formation of new supramolecular assemblies 5,5' and 6,6', respectively, in good yield. These derivatives have been characterized by NMR spectroscopy, IR, and X-ray diffraction studies. Derivative 5,5' are supramolecular metallacycles in which intramolecular aurophilic interactions between the Au(I) metal centers of the linkers are observed. Derivative 5 crystallizes as a single solid phase, whereas derivative 5' is characterized in the solid state as four different pseudo-polymorphs (5'a-d). Notably in the case of phase 5'd, a dimer of supramolecular metallacycles bounded by intermolecular aurophilic interactions is formed. Conversely, derivatives 6,6' present large structural diversity depending on the nature of the counterion. Derivative 6 is a supramolecular rectangle in which the Hg(II)-Hg(II) metal distance suggests mercurophilic interaction, whereas 6' crystallizes as two different pseudo-polymorphs 6'a,b, that is, a one-dimensional coordination polymer and one oligomer with no short Hg(II)-Hg(II) metal contacts, respectively. In derivatives 6,6', short contacts between the Hg(II) metal centers and fluorine atoms of the counterions are also observed, which may explain the counterion structural dependence of these supramolecular assemblies based on Hg(II) metal cyanide linker. Comparison of the different solid-state structures characterized highlights the importance of weak secondary interactions between the linkers for the formation supramolecular metallacycles from molecular clips 1,1' and suggests the range of energies required for these interactions to form metallacycles and to induce self-aggregation.

Self-Assembly of Cationic, Hetero- or Homonuclear Ruthenium(II) Macrocyclic Rectangles and Their Photophysical, Electrochemical, and Biological Studies

A series of supramolecular rectangles, including two mixed-metal Ru/Pt complexes, have been formed by the coordination-driven self-assembly of a range of arene-Ru "molecular clip" acceptors (1a-1d) with rigid dipyridyl-based ligands (2a-2d) over the course of 10 hours in solution. The isolated products were characterized by multinuclear NMR ((1)H and (13)C or (31)P), HR-ESI-MS and an X-ray diffraction study to support the ascribed two-component rectangular structures. The rectangles were further characterized by UV-Vis and fluorescence studies. The redox behaviors of rectangles 3ca and 3da were also determined using cyclic voltammetry. Additionally, the antitumor activities of the suite of rectangles were determined against various human cancer cell lines and significant activity was shown by complexes 3ca, 3da, 3cb, 3cc and 3cd, with IC(50) values as low as 2.65 μM.

Synthesis, structures and photoluminescence properties of silver(i) complexes with N,N′-di(pyrazin-2-yl)pyridine-2,6-diamine

Four silver complexes with N,N′-di(pyrazin-2-yl)pyridine-2,6-diamine (H2dpzpda) as ligand, [Ag2(H2dpzpda)2](ClO4)2 (1), [Ag2(H2dpzpda)2(ClO4)2] (DMF)2 (2), [Ag2(H2dpzpda)2](CF3SO3)2 (3), and [Ag2(H2dpzpda)(DMF)4](PF6)2·DMF (4) have been synthesized and structurally characterized by elemental analyses, IR spectroscopy and single-crystal X-ray diffractometer methods. The single-crystal X-ray determination revealed that the molecular structures 1 and 3 are all cationic bimetallic supramolecular rectangles, [Ag2(H2dpzpda)2]2+, in which two H2dpzpda ligands adopt bis-monodentate bridging mode connecting two linearly coordinated silver(I) ions. For 2, adjacent rectangles are then mutually linked via the Ag⋯Ag interaction to form an infinite 1D chain. The structure of complex 4 can be best described as a 1D ladder-like infinite chain, which is constructed via two crystallographically independent Ag(I) ions connected by the H2dpzpda ligand with a tetra-monodentate bridging mode. The emission of 1 and 3 is ascribed to a intra-ligand-based π*–π transition, while the emission origin of 4 is likely arising from inter-ligand charge-transfer transition. The emission of complex 2 is attributed to a inter-ligand charge-transfer transition. Moreover, two-photon excitation emission (TPEF) and two-photon absorption cross section of complex 2 were measured from TPEF via confocal microscope and Z-scan methods, for which two-photon cross section in solid state was deduced to be 43.4 ± 2.2 GM (800 nm).

Chiral and Extended π‐Conjugated Bis(2‐pyridyl)phospholes as Assembling N,P,N Pincers for Coordination‐Driven Synthesis of Supramolecular [2,2]Paracyclophane Analogues

Chiral, π-conjugated 3,4-butano-1-phenyl-2,5-bis(2-pyridyl)phosphole derivatives 1a(2,2') and 1a(3) with chiral trans-1,2-diol moieties and fused pinene derivatives, respectively, were prepared from the corresponding chiral diynes by using the Fagan-Nugent method. Their UV/Vis absorption and chiroptical properties (optical rotation and circular dichroism) were studied. Their behavior as N,P,N chelates towards coordination of Cu(I) and formation of chiral supramolecular assemblies with π-conjugated ditopic dicyano ligands was investigated. Chiral C(2)-symmetric rectangles that are [2,2]paracyclophane analogues were obtained, as demonstrated by X-ray crystallography. During the course of this study, the first stable water-soluble phosphole derivative (1a(2)·2 HCl) was prepared. Furthermore, achiral 3,4-butano-1-phenyl-2,5-bis(aza[4]helicene)phosphole 1a(4) was synthesized and displays extended π conjugation. A supramolecular rectangle was obtained by coordination to Cu(I) and assembly with a dicyano stilbene. This coordination-driven supramolecular assembly contains a total of four aza[4]helicene moieties and displays two types of π-π stacking interactions in the solid state, that is, between two helicene moieties and between one helicene and a bridging dicyano ligand. All the supramolecular arrangements are discussed by comparing them with previous work on the parent 3,4-butano-1-phenyl-2,5-bis(2-pyridyl)phosphole.

Structures of Metallosupramolecular Coordination Assemblies Can Be Obtained by Ion Mobility Spectrometry−Mass Spectrometry

Rigid rectangular, triangular, and prismatic supramolecular assemblies, cyclobis[(2,9-bis[trans-Pt(PEt(3))(2)(PF(6))]anthracene)(4,4'-dipyridyl)], cyclotris[(2,9-bis[trans-Pt(PEt(3))(2)(PF(6))]phenanthrene)(4,4'-dipyridyl)], and cyclotris[bis[cis-Pt(PEt(3))(2)(CF(3)SO(3))(2)]tetrakis(4-pyridyl)cyclobutadienecyclopentadienylcobalt(I)], respectively, based on dipyridyl ligands and square planar platinum coordination, have been investigated by ion mobility spectrometry-mass spectrometry (IMS-MS). Electrospray ionization-quadrupole and time-of-flight spectra have been obtained and fragmentation pathways assigned. Ion mobility studies give cross sections that compare very well with cross sections of the supramolecular rectangle and triangle species on the basis of X-ray bond distances. For the larger prism structures, agreement of experimental and calculated cross sections from molecular modeling is very good, indicating IMS-MS methods can be used to characterize complex self-assembled structures where X-ray or other spectroscopic structures are not available.

Structures, Fluorescent Properties of the d 10 Metal Ions Compounds Based on Molecular Clips

Two closed-shell d 10 metal ions complexes Cd 2 (L) 2 (I) 4 (1) and Zn 2 (L) 2 (Cl) 4 (DMF) 2 (2) were prepared from molecular clips, 2,2′-bis(benimidazol-1-ylmethyl)-biphenyl (L), and structurally characterized to investigate the structures. Both compounds 1 and 2 are bimetallic supramolecular rectangles in which two L ligands are connected by two tetrahedral coordinated metal ions. These units are connected together through weak π < eqid1 > π interaction, and 1 and 2 are crystallized in P2(1)/c and P-1 space group, respectively. Solid state fluorescent measurements exhibit the presence of ligand-based emission at 407 and 370 nm of compounds 1 and 2, respectively.

Functionalized Hydrophobic and Hydrophilic Self-Assembled Supramolecular Rectangles

The synthesis of six new, functionalized 180 degrees pyridyl donor ligands and their coordination-driven self-assembly into supramolecular rectangles is reported. Three of the new donors have been functionalized with hydrophobic straight chain alkane units (C6, C12, and C18) while the remaining three have been functionalized with derivatized di-, tetra-, and hexaethylene glycol hydrophilic units (DEG, TEG, and HEG, respectively). The resulting self-assembled hydrophobic and hydrophilic supramolecular rectangles have been fully characterized by multinuclear NMR and electrospray ionization mass spectrometry. Molecular force field modeling suggests that the functionalized rectangles range in size from roughly 3.0 x 2.9 to 3.0 x 6.0 nm2 in size.

π-Conjugated phosphole derivatives: synthesis, optoelectronic functions and coordination chemistry

pi-Conjugated organophosphorus derivatives have recently emerged as valuable building blocks for the tailoring of functional molecular materials. We have focused for ten years on the synthesis of phospholes bearing aromatic 2,5-substituents (phenyl, thienyl, pyridyl, etc.) and used these compounds as materials in fields as diverse as OLED's, WOLED's, non linear optics. Their properties (such as optical and electrochemical behaviour, thermal stability) can be finely tuned by functionalization at the P atom. Phosphole-based polymers have also been prepared by electropolymerization and have been used as sensors. More recently, phospholes substituted by one or two pyridyl groups have proven to act as multidentate ligands with original coordination properties. A diversity of supramolecular rectangles that stacked into columns in the solid state has been obtained, opening new perspectives in the coordination-driven supramolecular organization of pi-conjugated systems. Chiral pi-conjugated phospholes having a helical moiety have also been synthesized and spatially organized by using coordination to metallic ions, giving rise to sophisticated chiral complexes.