Photoactive building blocks for coordination complexes: Gilding 2,2′:6′,2″-terpyridine

The alkyne unit of 4`-ethynyl-2,2`:6`,2 ``-terpyridine has been functionalized with Ph(3)PAu, (2-tolyl)(3)PAu or Au(dppe)Au units to produce compounds 1-3, respectively. These derivatives have been characterized by electrospray mass spectrometry, solution (1)H and (13)C NMR, UV-Vis and emission spectroscopies, and single crystal X-ray diffraction. In the solid state, molecules of 1 or 2 pack with separated domains of tpy and R(3)PAu units; the tpy units in 2 (but not 1) exhibit face-to-face pi-stacking. Compound 3 crystallizes as 2(3)-CHCl(3), and the folded conformation of the dppe backbone results in a short (2.9470(8) angstrom) aurophilic interaction. Folded molecule 3 captures CHCl(3), preventing intramolecular face-to-face pi-interactions between the tpy units. In CH(2)Cl(2) solution, 1-3 are emissive when excited between 230 and 300 nm, but over minutes when lambda(ex) = 230 nm, the emission bands decay as the compounds photodegrade

Diastereoisomeric dinuclear ruthenium complexes of 2,5-di(2-pyridyl)thiazolo[5,4-d]thiazole

The first metal complexes of 2,5-di(2-pyridyl)thiazolo[5,4-d]thiazole (5) are described. X-Ray crystal structures are reported for the free ligand 5, a dinuclear copper complex 6 and the two diastereoisomers, 7meso and 7rac, of the dinuclear bis(2,2'-bipyridine)ruthenium complex. The two diastereoisomers of 7 and the 4,4'-dimethyl-2,2'-bipyridine analogue 8 are readily separated by cation exchange chromatography. 1H NMR and visible absorption spectra and electrochemical data for the four dinuclear ruthenium complexes reveal that these have relatively small HOMO–LUMO energy gaps and exhibit relatively weak metal–metal interactions

Do perfluoroarenearene and C–HF interactions make a difference to the structures of 4,2′:6′,4′′-terpyridine-based coordination polymers?

The consequences for the structures of coordination polymers of introducing fluoro substituents into the terminal phenyl domain of 4′-(biphenyl-4-yl)-4,2′:6′,4′′-terpyridine (1) have been investigated. Reaction between Cu(OAc)₂·H₂O and 4′-(2′,3′,4′,5′,6′-pentafluorobiphenyl-4-yl)-4,2′:6′,4′′-terpyridine (2) yields the one-dimensional coordination polymer [Cu₂(μ-OAc)₄(2)]n which contains paddle-wheel {Cu₂(OAc)₄} nodes bridged by ligands 2. The compound is isostructural with [Cu₂(μ-OAc)₄(1)]n. When Cu(OAc)₂·H₂O reacts with a 1 : 1 mixture of 1 and 2, [Cu₂(μ-OAc)₄(1)]n and [Cu₂(μ-OAc)₄(2)]n co-crystallize with 1 and 2 disordered over one ligand site; the one-dimensional coordination polymer is isostructural with each of [Cu₂(μ-OAc)₄(1)]n and [Cu₂(μ-OAc)₄(2)]n indicating that replacing H by F substituents in the peripheral arene ring has no effect on the overall solid-state structure: tpy⋯tpy π-stacking is preserved, arene⋯arene πH⋯πH interactions are replaced by perfluoroarene⋯arene πF⋯πH interactions, and H⋯H contacts are replaced by H⋯F interactions. In stark contrast to the latter observations, the reaction of Zn(OAc)₂·2H₂O with perfluoro derivative 2 yields [Zn₅(OAc)₁₀(2)₄·11H₂O]n as the dominant one-dimensional polymer; minor amounts of the anticipated polymer [Zn₂(μ-OAc)₄(2)]n are also formed. The solid-state structure of [Zn₅(OAc)₁₀(2)₄·11H₂O]n consists of quadruple-stranded polymer chains assembled from {Zn₅(2)₄} subchains interconnected by {Zn₅(OAc)₁₀} units. Within each chain, πF⋯πF and πH⋯πH stacking interactions are dominant, while the observed assembly of chains into sheets and π-stacking between arene units in adjacent sheets mimic the dominant interactions in the single-stranded chains observed in [Zn₂(μ-OAc)₄(1)]n, [Zn₂(μ-OAc)₄(2)]n, [Cu₂(μ-OAc)₄(1)]n, [Cu₂(μ-OAc)₄(2)]n and [Cu₂(μ-OAc)₄(1)]n·[Cu₂(μ-OAc)₄(2)]n

9-Anthracenyl-substitued pyridyl enones revisited : photoisomerism in ligands and silver(I) complexes

In solution, (E) to (Z)-isomerism is facile both in 3-(9-anthracenyl)-1-(pyridin-4-yl) propenone, 2, and in its silver(I) complex [Ag(2)(2)](+). The crystal structures of (E)-2, (Z)-2 and [Ag(E)-2(2)][SbF6] are presented, and the roles of edge-to-face and face-to-face p-interactions in the lattice are discussed. Solution NMR spectroscopic data suggest that the driving force for (E) to (Z) isomerization is intramolecular p-stacking of the pyridine and anthracene domains. The reversed enone 3-(9-anthracenyl)-1-(pyridin-4-yl) propen-3-one, (E)-3, and the silver(I) complex [Ag(E)-3(2)][SbF6] have been prepared and characterized, including a single crystal X-ray determination of the latter. Surprisingly, no p-stacking between anthracene or pyridine domains is observed in the solid state, and the crystal packing is dominated by Ag center dot center dot center dot F, CHanthracene center dot center dot center dot pi-pyridine and CH center dot center dot center dot F interactions. In contrast to (E)-2 and [Ag(E)-2(2)](+), neither (E)-3 nor [Ag(E)-3(2)](+) undergoes photoisomerization in solution

Zinc(II) coordination polymers, metallohexacycles and metallocapsules – do we understand self-assembly in metallosupramolecular chemistry : algorithms or serendipity?

Using a strategy of layering solvents and solutions of ligands and metal salts under ambient conditions, we observe the assembly of a discrete molecular metallohexacycle from ZnCl2 and 4`-(4-ethynylphenyl)-4,2`:6`,4 ``-terpyridine, polycatenated, triply interlocked metallocapsules from ZnI2 and 4`-(4-pyridyl)-4,2`:6`,4 ``-terpyridine, and 1-dimensional coordination polymers from either ZnCl2 or ZnI2 with 4`-4-( 3-chloropyridyl)-4,2`:6`,4 ``-terpyridine. On the basis of these studies and a comparison with related structures in the literature, we urge crystal engineers to be wary of drawing conclusions about self-assembly algorithms in solution using data from single crystal determinations

Disulfide struts : assembly motifs supporting a cuprocapsule

Condensation of 2-aminoethanethiol with 1,3-bis(3-formyl-2-hydroxyphenyl)-1,4,7,10,13-pentaoxatridecane in the presence of Cu(OAc)(2) and base is accompanied by oxidative coupling of pendant thiols with the formation of a disulfide-containing macrocycle H(2)1. This assembles the novel capsule [Cu-2(1)(2)] which hosts two CH2Cl2 guest molecules

Water-soluble alkylated bis{4'-(4-pyridyl)-2,2':6',2")-terpyridine}ruthenium(II) complexes for use as photosensitizers in water oxidation : a complementary experimental and TD-DFT investigation

A series of N-alkylated derivatives [RuL(2)][PF(6)](4) has been prepared from [Ru(pytpy)(2)][PF(6)](2) (N-alkyl substituent = 4-cyanobenzyl, 4-nitrobenzyl, ethyl, cyanomethyl, allyl, octyl). Solution NMR spectroscopic, electrochemical and photophysical properties are reported, along with the single crystal structure of [Ru(4)(2)][PF(6)](4) center dot H(2)O (4 = 4`-(4-(1- ethylpyridinio))- 2,2`: 6`,2`-terpyridine). Anion exchange leads to the water-soluble [RuL(2)][HSO(4)](4) salts (N-alkyl substituent = benzyl, 4- cyanobenzyl, 4- nitrobenzyl, ethyl, cyanomethyl, allyl, octyl) and the NMR spectroscopic signatures of pairs of hexafluoridophosphate and hydrogensulfate salts are compared. The change in anion has little effect on the energies of absorptions in the electronic spectra, although for all complexes, decreases in extinction coefficients are observed. The emission spectra and lifetimes for the hexafluoridophosphate and hydrogensulfate salts show similar trends; all exhibit an emission close to 720- 730 nm (lambda(ex) = 510 nm). For a given ligand, L, the emission lifetime decreases on going from [RuL(2)][PF(6)](4) to [RuL(2)][HSO(4)](4). However, trends are the same for both salts, i.e. the longest lived emitters are observed for N-ethyl, N-octyl and N-benzyl derivatives, and the shortest lived emitters are those containing cyano or nitro groups. Significantly, in the absorption spectra of the complexes, there is little variation in the energy of the MLCT band, suggesting that the character of the ligand orbital involved in the transition contains no character from the N-substituent. We have addressed this by carrying out a complementary DFT and TD-DFT study. Calculated absorption spectra predict a red shift in lambda(max) on going from [Ru(pytpy)(2)](2+) to [RuL(2)](4+), and little variation in lmax within the series of [RuL(2)](4+) complexes; these results agree with experimental observations. Analysis of the compositions of the MOs involved in the MLCT transitions explain the experimental observations, showing that there is no contribution from orbitals on the N-alkyl substituents, consistent with the fact that the nature of the N-substituents has little influence on the energy of the MLCT band. The theoretical results also reveal satisfactory agreement between calculated and crystallographic data for [Ru(1)(2)](4+) (1 = 4`-(4-(1- benzylpyridinio))-2,2`:6`,2`- terpyridine) and [Ru(4)(2)](4+)

A matter of greasy tails : interdigitation of alkyl chains in free and coordinated 4′-(4-dodecyloxyphenyl)-4,2′:6′,4″-terpyridines

The syntheses and single crystal structures of 4`-(4-dodecyloxyphenyl)-4,2`:6`,4 ``-terpyridine. 2, and [Zn-2(mu-OAc)(4)(2)(2)] are reported. Crystal packing is dominated by van der Waals interactions between fully extended alkyl chains producing lamellar structures in both compounds, and appears to be the reason for the formation of crystalline [Zn-2(mu-OAc)(4)(2)(2)] rather than a one-dimensional coordination polymer as observed for related compounds

Multinuclear zinc(II) complexes with Zn-6(mu-O)(6)(mu(3)-O)(2)- and Zn-5(mu-O)(3)(mu(3)-O)(3)-cluster cores

2-Ethoxy-6-(((2-hydroxyphenyl)imino)methyl)phenol, H21, reacts with zinc(II) chloride in basic conditions to give [Zn6(1)4Cl2(OH)2(OH2)2]. The electrospray mass spectrum of a MeOH solution of the bulk sample provides evidence for {Znn(1)n} species with n = 2–5, while the 1H NMR spectrum of a CDCl3 solution of the bulk sample indicates the presence of at least four species. Single crystals of 2{[Zn6(1)4Cl2(OH)2(OH2)(MeOH)]}·4MeOH·8H2O and 2{[Zn5(1)5(MeOH)(OH2)]}·6MeOH·H2O were obtained from the same solution of [Zn6(1)4Cl2(OH)2(OH2)2] in CH2Cl2/MeOH. Structural determinations confirm that these compounds contain {Zn6(μ-O)6(μ3-O)2}- and {Zn5(μ-O)3(μ3-O)3}-cluster cores, respectively, revealing that the O,O′,N,O″-donor set in [1]2− is suited to the assembly of relatively high nuclearity zinc(II)-containing clusters

Amalgamating metalloligands with coordination networks

The O4-cavity in [Cu{(R,R)-1}] ((R,R)-H21 = 1,6-bis(3-ethoxy-2-hydroxyphenyl)-(3R,4R)-(−)-cyclohexane-1,2-diyl-2,5-diazahexa-1,5-diene) binds HgBr2 to give P- and M-[Cu{(R,R)-1}HgBr2]. In the solid state, there is no diastereoselectivity with respect to the handedness of the helical twist adopted by the coordinated Schiff base ligand and [Cu{(R,R)-1}HgBr2] crystallizes with two independent molecules possessing M- and P-chirality, respectively, in the asymmetric unit. Single crystal structural data confirm that the same phenomenon is observed when [Ni{(R,R)-1}] is treated with HgBr2or Hg(CN)2. However, when an excess of Hg(NO3)2·H2O reacts with [Cu{(R,R)-1}], C-mercuration occurs in both 3-ethoxy-2-hydroxyphenyl rings in addition to the coordination of a Hg(NO3)2 unit within the O4-cavity of [Cu{(R,R)-1}]. This results in the formation of a two-dimensional coordination polymer network. The direct C-mercuration of a coordinated Schiff base ligand is not unique to the ligand in [Cu{(R,R)-1}], but also occurs during the reaction of [Cu(3)] (H23 = 1,7-bis(3-ethoxy-2-hydroxyphenyl)- 2,6-diazahepta-1,6-diene) with Hg(NO3)2·H2O proceeds in an analogous manner with C-mercuration occurs para to the phenolic oxygen atom