Guest‐Induced Photophysical Property Switching of Artificial Light‐Harvesting Dendrimers

An artificial light‐harvesting multiporphyrin dendrimer ( 8P_ZnP_FB ) composed of a focal freebase porphyrin ( P_FB ) with eight zinc(II) porphyrin ( P_Zn ) wings exhibited unique photophysical property switching in response to specific guest molecule binding. UV/Vis titration studies indicated stable 1:2 host–guest complex formation between 8P_ZnP_FB and meso‐tetrakis(4‐pyridyl)‐porphyrin ( TPyP ) for which the first and second association constants were estimated to be >10⁸ M ^?1 and 3.0×10⁷ M ^?1, respectively. 8P_ZnP_FB originally shows 94 % energy transfer efficiency from P_Zn to the focal P_FB . By the formation of the host–guest complex ( 8P_ZnP_FB? 2 TPyP ) the emission intensity of 8P_ZnP_FB is significantly decreased, and an ultrafast charge separation state is generated. The energy transfer process from P_Zn wings to the P_FB core in 8P_ZnP_FB is almost entirely switched to an electron transfer process by the formation of 8P_ZnP_FB? 2 TPyP .     

Tridentate anilido‐aldimine magnesium and zinc complexes as efficient catalysts for ring‐opening polymerization of ε‐caprolactone and L‐lactide

A novel tridentate anilido‐aldimine ligand, [o‐C₆H₄(NHAr)? HC?NCH₂CH₂NMe₂] (Ar = 2,6‐ⁱPr₂C₆H₃, L ‐H, 1 ), has been prepared by the condensation of N, N‐dimethylethylenediamine with one molar equivalent of 2‐fluoro‐benzaldehyde in hexane, followed by the addition of the lithium salt of diisopropylaniline in THF. Magnesium (Mg) and zinc (Zn) complexes supported by the tridentate anilido‐aldimine ligand have been synthesized and structurally characterized. Reaction of L ‐H ( 1 ) with an equivalent amount of MgⁿBu₂ or ZnEt₂ produces the monomeric complex [ L MgⁿBu] ( 2 ) or [ L ZnEt] ( 3 ), respectively. Experimental results show that complexes 2 and 3 are efficient catalysts for ring‐opening polymerization of ε‐caprolactone (CL) and L ‐lactide (LA) in the presence of benzyl alcohol and catalyze the polymerization of ε‐CL and L ‐LA in a controlled fashion yielding polymers with a narrow polydispersity index. In both polymerizations, the activity of Mg complex 2 is higher than that of Zn complex 3 , which is probably due to the higher Lewis acidity and better oxophilic nature of Mg²⁺ metal. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4927–4936, 2009     

Well‐Defined Molecular Magnesium Hydride Clusters: Relationship between Size and Hydrogen‐Elimination Temperature

A new tetranuclear magnesium hydride cluster, [{ NN ‐(MgH)₂}₂], which was based on a N? N‐coupled bis‐β‐diketiminate ligand ( NN ^2?), was obtained from the reaction of [{ NN ‐(MgnBu)₂}₂] with PhSiH₃. Its crystal structure reveals an almost‐tetrahedral arrangement of Mg atoms and two different sets of hydride ions, which give rise to a coupling in the NMR spectrum (J=8.5 Hz). To shed light on the relationship between the cluster size and H₂ release, the thermal decomposition of [{ NN ‐(MgH)₂}₂] and two closely related systems that were based on similar ligands, that is, an octanuclear magnesium hydride cluster and a dimeric magnesium hydride species, have been investigated in detail. A lowering of the H₂‐desorption temperature with decreasing cluster size is observed, in line with previously reported theoretical predictions on (MgH₂)_n model systems. Deuterium‐labeling studies further demonstrate that the released H₂ solely originates from the oxidative coupling of two hydride ligands and not from other hydrogen sources, such as the β‐diketiminate ligands. Analysis of the DFT‐computed electron density in [{ NN ‐(MgH)₂}₂] reveals a counterintuitive interaction between two formally closed‐shell H^? ligands that are separated by 3.106 Å. This weak interaction could play an important role in H₂ desorption. Although the molecular product after H₂ release could not be characterized experimentally, DFT calculations on the proposed decomposition product, that is, the low‐valence tetranuclear Mg(I) cluster [( NN ‐Mg₂)₂], predict a structure with two almost‐parallel, localized Mg? Mg bonds. As in a previously reported β‐diketiminate Mg^I dimer, the Mg? Mg bond is not characterized by a bond critical point, but instead displays a local maximum of electron density midway between the atoms, that is, a non‐nuclear attractor (NNA). Interestingly, both of the NNAs in [( NN ‐Mg₂)₂] are connected through a bond path that suggests that there is bonding between all four Mg^I atoms.     

Magnesium complexes incorporated by sulfonate phenoxide ligands as efficient catalysts for ring‐opening polymerization of ε‐caprolactone and trimethylene carbonate

Two novel sulfonate phenol ligands—3,3′‐di‐tert‐butyl‐2′‐hydroxy‐5,5′,6,6′‐tetramethyl‐biphenyl‐2‐yl 4‐X‐benzenesulfonate (X?CF₃, L^CF3 ‐H, and X?OCH₃, L^OMe ‐H)—were prepared through the sulfonylation of 3,3′‐di‐tert‐butyl‐5,5′,6,6′‐tetramethylbiphenyl‐2,2′‐diol with the corresponding 4‐substituted benzenesulfonyl chloride (1 equiv.) in the presence of excess triethylamine. Magnesium (Mg) complexes supported by sulfonate phenoxide ligands were synthesized and characterized structurally. The reaction of MgⁿBu₂ with L‐H (2 equiv.) produces the four‐coordinated monomeric complexes ( L^CF3 )₂Mg ( 1 ) and ( L^OMe )₂Mg ( 2 ). Complexes 1 and 2 are efficient catalysts for the ring‐opening polymerization of ε‐caprolactone (ε‐CL) and trimethylene carbonate (TMC) in the presence of 9‐anthracenemethanol; complex 1 catalyzes the polymerization of ε‐CL and TMC in a controlled manner, yielding polymers with the expected molecular weights and narrow polydispersity indices (PDIs). In ε‐CL polymerization, the activity of complex 1 is greater than that of complex 2 , likely because of the greater Lewis acidity of Mg²⁺ metal caused by the electron‐withdrawing substitute trifluoromethyl (? CF₃) at the 4‐position of the benzenesulfonate group. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3564–3572, 2010     

Preparation and Characterization of Mg‐Zr Mixed Oxide Aerogels and Their Application as Aldol Condensation Catalysts

A series of Mg‐Zr mixed oxides with different nominal Mg/ (Mg+Zr) atomic ratios, namely 0, 0.1, 0.2, 0.4, 0.85, and 1, is prepared by alcogel methodology and fundamental insights into the phases obtained and resulting active sites are studied. Characterization is performed by X‐ray diffraction, transmission electron microscopy, X‐ray photoelectron spectroscopy, N₂ adsorption–desorption isotherms, and thermal and chemical analysis. Cubic Mg_xZr_1?xO_2?x solid solution, which results from the dissolution of Mg²⁺ cations within the cubic ZrO₂ structure, is the main phase detected for the solids with theoretical Mg/ (Mg+Zr) atomic ratio ≤0.4. In contrast, the cubic periclase (c‐MgO) phase derived from hydroxynitrates or hydroxy precursors predominates in the solid with Mg/(Mg+Zr)=0.85. c‐MgO is also incipiently detected in samples with Mg/(Mg+Zr)=0.2 and 0.4, but in these solids the c‐MgO phase mostly arises from the segregation of Mg atoms out of the alcogel‐derived c‐Mg_xZr_1?xO_2?x phase during the calcination process, and therefore the species c‐MgO and c‐Mg_xZr_1?xO_2?x are in close contact. Regarding the intrinsic activity in furfural–acetone aldol condensation in the aqueous phase, these Mg? O? Zr sites located at the interface between c‐Mg_xZr_1?xO_2?x and segregated c‐MgO display a much larger intrinsic activity than the other noninterface sites that are present in these catalysts: Mg? O? Mg sites on c‐MgO and Mg? O? Zr sites on c‐Mg_xZr_1?xO_2?x. The very active Mg? O? Zr sites rapidly deactivate in the furfural–acetone condensation due to the leaching of active phases, deposition of heavy hydrocarbonaceous compounds, and hydration of the c‐MgO phase. Nonetheless, these Mg‐Zr materials with very high specific surface areas would be suitable solid catalysts for other relevant reactions catalyzed by strong basic sites in nonaqueous environments.     

Enhanced Reactivities of Iron(IV)‐Oxo Porphyrin π‐Cation Radicals in Oxygenation Reactions by Electron‐Donating Axial Ligands

The proximal axial ligand in heme iron enzymes plays an important role in tuning the reactivities of iron(IV)‐oxo porphyrin π‐cation radicals in oxidation reactions. The present study reports the effects of axial ligands in olefin epoxidation, aromatic hydroxylation, alcohol oxidation, and alkane hydroxylation, by [(tmp)^+. Fe^IV(O)(p‐Y‐PyO)]⁺ ( 1 ‐Y) (tmp=meso‐tetramesitylporphyrin, p‐Y‐PyO=para‐substituted pyridine N‐oxides, and Y=OCH₃, CH₃, H, Cl). In all of the oxidation reactions, the reactivities of 1 ‐Y are found to follow the order 1 ‐OCH₃ > 1 ‐CH₃ > 1 ‐H > 1 ‐Cl; negative Hammett ρ values of ?1.4 to ?2.7 were obtained by plotting the reaction rates against the σ_p values of the substituents of p‐Y‐PyO. These results, as well as previous ones on the effect of anionic nucleophiles, show that iron(IV)‐oxo porphyrin π‐cation radicals bearing electron‐donating axial ligands are more reactive in oxo‐transfer and hydrogen‐atom abstraction reactions. These results are counterintuitive since iron(IV)‐oxo porphyrin π‐cation radicals are electrophilic species. Theoretical calculations of anionic and neutral ligands reproduced the counterintuitive experimental findings and elucidated the root cause of the axial ligand effects. Thus, in the case of anionic ligands, as the ligand becomes a better electron donor, it strengthens the FeO? H bond and thereby enhances its H‐abstraction activity. In addition, it weakens the Fe?O bond and encourages oxo‐transfer reactivity. Both are Bell–Evans–Polanyi effects, however, in a series of neutral ligands like p‐Y‐PyO, there is a relatively weak trend that appears to originate in two‐state reactivity (TSR). This combination of experiment and theory enabled us to elucidate the factors that control the reactivity patterns of iron(IV)‐oxo porphyrin π‐cation radicals in oxidation reactions and to resolve an enigmatic and fundamental problem.     

Crystal structure,shape analysis and bioactivity of new LiI,NaI and MgII complexes with 1,10‐phenanthroline and 2‐(3,4‐dichlorophenyl)acetic acid

Reactions of 1,10‐phenanthroline (phen) and 2‐(3,4‐dichlorophenyl)acetic acid (dcaH) with M_n(CO₃) (M = Li^I, Na^I and Mg^II; n = 1 and 2) in MeOH yield the mononuclear lithium complex aqua[2‐(3,4‐dichlorophenyl)acetato‐κO](1,10‐phenanthroline‐κ²N,N′)lithium(I), [Li(C₈H₅Cl₂O₂)(C₁₂H₈N₂)(H₂O)] or [Li(dca)(phen)(H₂O)] ( 1 ), the dinuclear sodium complex di‐μ‐aqua‐bis{[2‐(3,4‐dichlorophenyl)acetato‐κO](1,10‐phenanthroline‐κ²N,N′)sodium(I)}, [Na₂(C₈H₅Cl₂O₂)₂(C₁₂H₈N₂)₂(H₂O)₂] or [Na₂(dca)₂(phen)₂(H₂O)₂] ( 2 ), and the one‐dimensional chain magnesium complex catena‐poly[[[diaqua(1,10‐phenanthroline‐κ²N,N′)magnesium]‐μ‐2‐(3,4‐dichlorophenyl)acetato‐κ²O:O′] 2‐(3,4‐dichlorophenyl)acetate monohydrate], {[Mg(C₈H₅Cl₂O₂)(C₁₂H₈N₂)(H₂O)₂](C₈H₅Cl₂O₂)·H₂O}_n or {[Mg(dca)(phen)(H₂O)₂](dca)·H₂O}_n ( 3 ). In these complexes, phen binds via an N,N′‐chelate pocket, while the deprotonated dca^? ligands coordinate either in a monodentate (in 1 and 2 ) or bidentate (in 3 ) fashion. The remaining coordination sites around the metal ions are occupied by water molecules in all three complexes. Complex 1 crystallizes in the triclinic space group P with one molecule in the asymmetric unit. The Li⁺ ion adopts a four‐coordinated distorted seesaw geometry comprising an [N₂O₂] donor set. Complex 2 crystallizes in the triclinic space group P with half a molecule in the asymmetric unit, in which the Na⁺ ion adopts a five‐coordinated distorted spherical square‐pyramidal geometry, with an [N₂O₃] donor set. Complex 3 crystallizes in the orthorhombic space group P2₁2₁2₁, with one Mg²⁺ ion, one phen ligand, two dca^? ligands and three water molecules in the asymmetric unit. Both dcaH ligands are deprotonated, however, one dca^? anion is not coordinated, whereas the second dca^? anion coordinates in a bidentate fashion bridging two Mg²⁺ ions, resulting in a one‐dimensional chain structure for 3 . The Mg²⁺ ion adopts a distorted octahedral geometry, with an [N₂O₄] donor set. Complexes 1 – 3 were evaluated against urease and α‐glucosidase enzymes for their inhibition potential and were found to be inactive.     

Synthesis,Structure, and Photophysical Properties of the Di‐ and Trinuclear Phosphine‐Diimine Complexes of Copper(I)

Reactions of [Cu(NCMe)₄]⁺ with stoichiometric amount of diphosphine R₂P–(C₆H₄)_n–PR₂, (R = NC₄H₄, n = 1; R = Ph, n = 1, 2, 3) or tri‐phosphine 1, 3, 5‐(PPh₂–C₆H₄–)₃–C₆H₃ ligands give the corresponding di‐ or trinuclear copper(I) acetonitrile‐phosphine complexes 1 – 5 . Substitution of the labile acetonitrile groups with chelating aromatic diimines – 2, 2′‐bipyridine (bpy), 1, 10‐phenanthroline (phen), 5, 6‐dimethyl‐1, 10‐phenanthroline (dmp), 5, 6‐dibromo‐1, 10‐phenanthroline (phenBr₂) – gives the corresponding substituted compounds 6 – 16 . In all complexes 1 – 16 each central Cu^I atom has tetrahedral configuration completed with two N‐ and two P‐donor groups. The compounds obtained were characterized using elemental analysis, ESI‐MS, X‐ray crystallography, and NMR spectroscopy. All phosphine‐diimine compounds 6 – 16 are photoluminescent at room temperature both in dichloromethane solution and in solid state (λ_ex = 385 nm). In CH₂Cl₂ solution the maxima of emission bands are found in a range 540–640 nm, and in solid in a similar range 538–620 nm. Emission of 6 – 16 is assigned to the triplet excited state dominated by the charge transfer transitions with contribution of the MLCT character.     

Ring‐opening polymerization of β‐butyrolactone catalyzed by efficient magnesium and zinc complexes derived from tridentate anilido‐aldimine ligand

Magnesium (Mg) and zinc (Zn) complexes incorporating tridentate anilido‐aldimine ligand, (E)‐2, 6‐diisopropyl‐N‐(2‐((2‐(piperidin‐1‐yl)ethylimino)methyl)phenyl)aniline ( AA ^Pip ‐H, 1 ), were synthesized and structurally characterized. The reaction of AA ^Pip ‐H ( 1 ) with MgⁿBu₂ or ZnEt₂ in equivalent proportions afforded the monomeric complex [( AA ^Pip )MgⁿBu] ( 2 ) or [( AA ^Pip )ZnEt] ( 3 ), respectively. The coordination modes of these complexes differ in the solid state: Mg complex 2 shows a four‐coordinated and distorted tetrahedral geometry, whereas Zn complex 3 adopts a trigonal planar geometry with a three‐coordinated Zn center. Complexes 2 and 3 are efficient catalysts for the ring‐opening polymerization of β‐butyrolactone (β‐BL) in the presence of 9‐anthracenemethanol (9‐AnOH). The polymerization of β‐BL with the Zn catalyst system is demonstrated in a living fashion with a narrow polydispersity index, PDI = 1.01–1.10. The number‐averaged molecular weight (M_n) of the produced poly(3‐hydroxybutyrate) (PHB) is quite close to the expected M_n over diverse molar ratios of monomer to 9‐AnOH. A greater ratio of monomer to alcohol catalyzed by Zn complex 3 served to form PHB with a large molecular weight (M_n > 60000). An effective method to prepare PHB‐b‐PCL and PEG‐b‐PHB by the ring‐opening copolymerization of β‐BL catalyzed by zinc complex 3 is reported. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Synthesis,Characterization and X‐ray Crystal Structure of a Chromium(III) Complex Obtained from a Proton‐Transfer Compound Containing 1,10‐Phenanthroline‐2,9‐dicarboxylic Acid and 2,6‐Pyridinediamine

The novel 1,10‐phenanthroline‐2,9‐dicarboxylate containing Chromium(III) complex, (pydaH)[Cr(phendc)₂] · 5H₂O, was synthesized using proton‐transfer compound LH₂, (pydaH₂)²⁺(phendc)^2?, (pyda: 2,6‐pyridinediamine; phendcH₂: 1,10‐phenanthroline‐2,9‐dicarboxylic acid) and thoroughly characterized by elemental analysis, IR spectroscopy, X‐ray crystallography and cyclic voltammetry. The complex crystallizes in the monoclinic space group P2₁/n with four formula units in the unit cell. The unit cell dimensions are: a = 13.962(3) Å, b = 14.529(3) Å, c = 16.381(3) Å and β = 106.691(4)°. In this complex, 1,10‐phenanthroline‐2,9‐dicarboxylate acts as a tridentate ligand and the lattice is composed of anionic hexacoordinated complex, [Cr(phendc)₂]^?, 2,6‐pyridiniumdiamine counter ion, (pydaH)⁺, and five lattice water molecules. Crystallographic characterization revealed that the resulting supramolecular structure is strongly stabilized by complicated network of hydrogen bonds between the crystallization water molecules, counter ion and both coordinated and uncoordinated carboxylate groups. There is no relevant π‐π interaction for this anionic complex between pyda or phendc moieties. The electrochemical studies indicated over potential for both the cathodic and anodic peaks of the complex with respect to the free Cr³⁺ ion, as a consequence of the energy requirement for rearrangement of the ligand at electrode surface.     

Alkali‐Metal‐Mediated Magnesiations of an N‐Heterocyclic Carbene: Normal,Abnormal, and “Paranormal” Reactivity in a Single Tritopic Molecule

Herein the sodium alkylmagnesium amide [Na₄Mg₂(TMP)₆(nBu)₂] (TMP=2,2,6,6‐tetramethylpiperidide), a template base as its deprotonating action is dictated primarily by its 12 atom ring structure, is studied with the common N‐heterocyclic carbene (NHC) IPr [1,3‐bis(2,6‐diisopropylphenyl)imidazol‐2‐ylidene]. Remarkably, magnesiation of IPr occurs at the para‐position of an aryl substituent, sodiation occurs at the abnormal C4 position, and a dative bond occurs between normal C2 and sodium, all within a 20 atom ring structure accommodating two IPr^2?. Studies with different K/Mg and Na/Mg bimetallic bases led to two other magnesiated NHC structures containing two or three IPr^? monoanions bound to Mg through abnormal C4 sites. Synergistic in that magnesiation can only work through alkali‐metal mediation, these reactions add magnesium to the small cartel of metals capable of directly metalating a NHC.     

A two‐dimensional CdII coordination polymer with 2,2′‐(disulfanediyl)dibenzoate and 1,10‐phenanthroline ligands

In poly[[μ₃‐2,2′‐(disulfanediyl)dibenzoato‐κ⁵O:O,O′:O′′,O′′′](1,10‐phenanthroline‐κ²N,N′)cadmium(II)], [Cd(C₁₄H₈O₄S₂)(C₁₂H₈N₂)]_n, the asymmetric unit contains one Cd^II cation, one 2,2′‐(disulfanediyl)dibenzoate anion (denoted dtdb²⁻) and one 1,10‐phenanthroline ligand (denoted phen). Each Cd^II centre is seven‐coordinated by five O atoms of bridging/chelating carboxylate groups from three dtdb²⁻ ligands and by two N atoms from one phen ligand, forming a distorted pentagonal–bipyramidal geometry. The Cd^II cations are bridged by dtdb²⁻ anions to give a two‐dimensional (4,4) layer. The layers are stacked to generate a three‐dimensional supramolecular architecture via a combination of aromatic C—H...π and π–π interactions. The thermogravimetric and luminescence properties of this compound were also investigated.     

Synthesis,Characterization, Redox Properties,and Photodynamics of Donor–Acceptor Nanohybrids Composed of Size‐Controlled Cup‐Shaped Nanocarbons and Porphyrins

Cup‐shaped nanocarbons (CNC) generated by the electron‐transfer reduction of cup‐stacked carbon nanotubes have been functionalized with porphyrins (H₂P) as light‐capturing chromophores. The resulting donor–acceptor nanohybrid has been characterized by thermogravimetric analysis (TGA), Raman and IR spectroscopy, transmission electron microscopy, elemental analysis, and UV/Vis spectroscopy. The weight of the porphyrins attached to the cup‐shaped nanocarbons was determined as 20 % by TGA and elemental analysis. The UV/Vis absorption spectrum of CNC? (H₂P)_n in DMF agrees well with that obtained by the superposition of reference porphyrin (ref‐H₂P) and cup‐shaped nanocarbons. The photoexcitation of the CNC? (H₂P)_n nanohybrid results in formation of the charge‐separated (CS) state to attain the longest CS lifetime (0.64±0.01 ms) ever reported for donor–acceptor nanohybrids, which may arise from efficient electron migration following the charge separation. The formation of a radical ion pair was detected directly by electron spin resonance (ESR) measurements under photoirradiation of CNC? (H₂P)_n with a high‐pressure mercury lamp in frozen DMF at 153 K. The observed ESR signal at g=2.0044 agrees with that of ref‐H₂P^.+ produced by one‐electron oxidation with [Ru(bpy)₃]³⁺ in deaerated CHCl₃, indicating the formation of H₂P^.+. The electron‐acceptor ability of the reference CNC compound (ref‐CNC) was also examined by the electron‐transfer reduction of ref‐CNC by a series of semiquinone radical anions.     

Polymeric aqua­(μ4‐di­hydrogen benzene‐1,2,4,5‐tetra­carboxylato)(1,10‐phen­anthroline)cobalt(II)

In the title compound, poly[[aqua(1,10‐phenanthroline)­cobalt(II)]‐μ₄‐di­hydrogen benzene‐1,2,4,5‐tetra­carboxyl­ato], [Co(C₁₀H₄O₈)(C₁₂H₈N₂)(H₂O)]_n, each cobalt(II) cation has an octahedral geometry completed by one aqua O atom, three carboxy O atoms belonging to three H₂TCB²⁻ anions (H₂TCB²⁻ is di­hydrogen ­benzene‐1,2,4,5‐tetra­carboxyl­ate) and two N atoms from a 1,10‐phenanthroline mol­ecule. In the asymmetric unit, there are two half H₂TCB²⁻ anions lying about independent inversion centres. The bridging H₂TCB²⁻ anions have two coordination modes, viz.μ₂‐H₂TCB²⁻ and μ₄‐H₂TCB²⁻, resulting in a two‐dimensional coordination polymer. Furthermore, a three‐dimensional network is formed by O_carboxy⋯O_carboxy hydrogen‐bond interactions, with H⋯A distances in the range 1.69–1.82 Å, and O_carboxy⋯O_water interactions, with H⋯A distances in the range 1.91–1.94 Å.     

catena‐Poly[[bis[aqua­(1,10‐phenanthroline)lead(II)]‐di‐μ3‐5‐carboxy‐3‐sulfonatobenzoato] dihydrate]

In the centrosymmetric title polymer, catena‐poly[[bis[aqua­(1,10‐phenanthroline‐κ²N,N′)lead(II)]‐di‐μ₃‐5‐carboxy‐3‐sulfonatobenzoato‐1:2:1′κ⁴O³:O¹,O^1′:O¹;2′:1:2κ⁴O¹:O¹,O^1′:O³] dihydrate], {[Pb(C₈H₄O₇S)(C₁₂H₈N₂)(H₂O)]·H₂O}_n, each seven‐coordinate lead(II) ion is bound by five O atoms from one water molecule and three 5‐sulfoisophthalate (sip) anions, and by two N atoms from a 1,10‐phenanthroline (phen) ligand. The sip sulfonate group is monodentate. One O atom of the sip carboxyl­ate group is chelated to one Pb²⁺ cation, with the other also bridging an adjacent Pb²⁺ cation. The carboxyl group is uncoordinated. This unusual coordination results in a chain structure along the b axis, which is linked by strong intermolecular hydrogen bonds into a three‐dimensional network.     

Large Porphyrin Squares from the Self‐Assembly of meso‐Triazole‐Appended L‐Shaped meso–meso‐Linked ZnII–Triporphyrins: Synthesis and Efficient Energy Transfer

meso‐Triazolyl‐appended Zn^II–porphyrins were readily prepared by Cu^I‐catalyzed 1,3‐dipolar cycloaddition of benzyl azide to meso‐ethynylated Zn^II–porphyrin (click chemistry). In noncoordinating CHCl₃ solvent, spontaneous assembly occurred to form tetrameric array ( 3 )₂ from meso–meso‐linked diporphyrins 3 , and dodecameric porphyrin squares ( 4 )₄ and ( 5 )₄ from the L ‐shaped meso–meso‐linked triporphyrins 4 and 5 . The structures of these assemblies were examined by ¹H NMR spectra, absorption spectra, and their gel permeation chromatography (GPC) retention time. Furthermore, the structures of the dodecameric porphyrin squares ( 4 )₄ and ( 5 )₄ were probed by small‐ and wide‐angle X‐ray scattering (SAXS/WAXS) measurements in solution using a synchrotron source. Excitation‐energy migration processes in these assemblies were also investigated in detail by using both steady‐state and time‐resolved spectroscopic methods, which revealed efficient excited‐energy transfer (EET) between the meso–meso‐linked Zn^II–porphyrin units that occurred with time constants of 1.5 ps^?1 for ( 3 )₂ and 8.8 ps^?1 for ( 5 )₄.     

Bis(μ‐2‐sulfonatobenzoato)bis[(1,10‐phenanthroline)­lead(II)] dihydrate

In the title centrosymmetric dimer, [Pb₂(sbc)₂(phen)₂]·2H₂O [sbc is the 2‐sulfonatobenzoate dianion (C₇H₄O₅S) and phen is 1,10‐phenanthroline (C₁₂H₈N₂)], each Pb^II ion is six‐coordinated by four O atoms, viz. carboxyl­ate and sulfonate O atoms from two sbc anions, and two N atoms from a 1,10‐phenanthroline ligand. One 1,10‐phenanthroline ligand and the carboxyl­ate group of one sbc ligand are chelated to each Pb^II cation, and the sulfonate group of the other sbc unit is monodentate. One O atom of the chelated carboxyl­ate group also bridges to the other Pb^II cation, so that each pair of Pb^II ions is bridged by two sbc anions and has the same coordination environment, forming a dinuclear ring. Each pair of Pb^II ions is thus connected by two different kinds of bridges, namely a carboxyl­ate short bridge and a carboxyl­ate–sulfonate long bridge. There is also a special position of site symmetry at the centre of the two Pb^II cations.     

The salt‐type 1:2 adduct of meso‐5,5,7,12,12,14‐hexa‐C‐methyl‐1,4,8,11‐tetraazacyclotetradecane (tet‐a) and 5‐nitroisophthalic acid forms a hydrogen‐bonded sheet ­structure containing two configur­ational isomers of [(tet‐a)H2]2+

The title compound, meso‐5,7,7,12,14,14‐hexa­methyl‐4,11‐di­aza‐1,8‐diazo­nia­cyclo­tetra­decane bis(3‐carboxy‐5‐nitro­benz­oate), C₁₆H₃₈N₄²⁺·2C₈H₄NO₆^?, is a salt in which the cation is present as two configurational isomers, disordered across a common centre of inversion in P, with occupancies of 0.847 (3) and 0.153 (3). The anions are linked into chains by a single O—H?O hydrogen bond [H?O 1.71 Å, O?O 2.5063 (15) Å and O—H?O 156°] and the cations link these anion chains into sheets by means of a range of N—H?O hydrogen bonds [H?O 1.81–2.53 Å, N?O 2.718 (5)–3.3554 (19) Å and N—H?O 146–171°].     

Magnesium(II) Complexes with High Emission: The Distinct Charge‐Transfer Process from Transition Metal

Generally, the first‐row transition‐metal complexes are notorious in luminescence materials because of their metal‐ligand charge transfer in emission process. Herein, we rationally used magnesium instead the first‐row transition metal to coordinate with 2‐(anthracen‐9‐yl)‐1H‐imidazo[4,5‐f][1,10]phenanthroline (AIP) in the construction of luminescent complexes. Further investigation revealed AIP could work as detector for quantitative determination of Mg²⁺ cation. Comparing to other divalent cations, this fluorescence sensor exhibited high selectivity for the quantitative determination of Mg²⁺ with the low limit of detection (5 × 10^–7 m ). Through X‐ray single crystal diffraction, the crystal structures of [Mg(AIP₂)(NO₃)₂ · (H₂O)₄] ( 1 ), [Mn(AIP)(NO₃) · EtOH] ( 2 ), and [Co₂(AIP)₂Cl₄ · (MeOH)₂] ( 3 ) were observed in various arrangements. The theory calculations based on crystal structures indicated the Mg^II complex undergoes distinct charge‐transfer process from other transition‐metals based compounds, in which charge‐transfer excited‐state lifetimes were deactivated rapidly through metal‐to‐ligand charge‐transfer (MLCT) process. This study provided insight into construction of luminescence compounds by using d⁰ metals in main groups instead of transition metals.     

Adducts of 1,1,1‐tris(4‐hydroxyphenyl)ethane with diamines: three‐dimensional hydrogen‐bonded frameworks formed with 1,6‐diaminohexane and 2,2′‐bipyridyl

The adduct 1,6‐di­amino­hexane–1,1,1‐tris(4‐hydroxy­phenyl)­ethane (1/2) is a salt {hexane‐1,6‐diyldiammonium–4‐[1,1‐bis(4‐hydroxyphenyl)ethyl]phenolate (1/2)}, C₆H₁₈N₂²⁺·2C₂₀H₁₇O₃^?, in which the cation lies across a centre of inversion in space group P. The anions are linked by two short O—H?O hydrogen bonds [H?O 1.74 and 1.76 Å, O?O 2.5702 (12) and 2.5855 (12) Å, and O—H?O 168 and 169°] into a chain containing two types of R(24) ring. Each cation is linked to four different anion chains by three N—H?O hydrogen bonds [H?O 1.76–2.06 Å, N?O 2.6749 (14)–2.9159 (14) Å and N—H?O 156–172°]. In the adduct 2,2′‐bipyridyl–1,1,1‐tris(4‐hydroxy­phenyl)­ethane (1/2), C₁₀H₈N₂·2C₂₀H₁₈O₃, the neutral di­amine lies across a centre of inversion in space group P2₁/n. The tris­(phenol) mol­ecules are linked by two O—H?O hydrogen bonds [H?O both 1.90 Å, O?O 2.7303 (14) and 2.7415 (15) Å, and O—H?O 173 and 176°] into sheets built from R(38) rings. Pairs of tris­(phenol) sheets are linked via the di­amine by means of a single O—H?N hydrogen bond [H?N 1.97 Å, O?N 2.7833 (16) Å and O—H?N 163°].