Search

The design and development of functional materials with real-life applications are highly demanding. Understanding and controlling inter- and intra-molecular interactions provide opportunities to design new materials. A judicious manipulation of the molecular structure significantly alters such interactions and can boost selected properties and functions of the material. There is burgeoning evidence of the beneficial effects of non-covalent interactions (NCIs), showing that manipulating NCIs may generate functional materials with a wide variety of physical properties leading to applications in catalysis, drug delivery, crystal engineering

Two new organo-europium complexes (OEuCs) [Eu(tfac)3(TB-Im)] (Eu1) [Eu(hfac)3(TB-Im)] (Eu2) incorporating fluorinated (hexafluoroacetylacetone; Hhfaa) or hemi-fluorinated (trifluoroacetylacetone; Htfac) β-diketones together with the large bite angle N^N ligand (2-(4-thiazolyl)benzimidazole; TB-Im) have been synthesized and characterized. The structure of the complexes has been established by single crystal X-ray diffraction (SC-XRD) analysis and shows that the coordination sphere is composed of a EuO6N2 core (octacoordinated). Continuous shape measures (CShMs) revealed that the geometry around Eu(III) is trigonal dodecahedral with approximate D2d-symmetry. Efficient red emission is observed for both the complexes in solution with a fairly large photoluminescence quantum yield (PLQY (QLEu) = 39.00–47.00%). Furthermore, by utilizing the experimental photoluminescence (PL) data and theoretical modelling employing density functional theory (DFT) in conjunction with LUMPAC, energy transfer (ET) and back energy transfer rates were calculated, and an ET mechanism for the sensitized PL is proposed and discussed in detail. Finally, the complexes were used as an emitting layer (EML) to fabricate 20 organic light emitting diodes (OLEDs) by varying the doping concentration. Interestingly, both the complex-based OLEDs at 4 wt% doping concentration display white electroluminescence (EL) with the brightness (B) = 100.5–364.1 cd m−2 at very low turn-on voltage (Vturn-on) = 3.9–4.6 V. The overall electroluminescence performance of Eu1 and Eu2 is higher than that of the reported europium based single component white-OLEDs.

There is a need to develop rapidly responsive chemical sensors for the detection of low concentrations of volatile organic solvents (VOCs). Platinum pincer complexes have shown promise as sensors because of their colours and vapochromic and solvatochromic properties, that may be related to the non-covalent interactions between the pincer complexes and the guest VOCs. Here we report an investigation into a series of Pt(II) complexes based on the 1,3-di(pyridine)benzene tridentate (N⁁C⁁N) skeleton with the formula [Pt(N⁁C(R)⁁N)(CN)] (R = C(O)Me 2, C(O)OEt 3, C(O)OPh 4) with the fourth coordination site occupied by a cyanide ligand. Solid-state samples of the complexes have been tested with a range of volatiles including methanol, ethanol, acetone, dichloromethane and water, and while 2 displays thermochromism, 3 and 4 display rapidly reversible vapochromism and solvatochromism. These results are correlated with X-ray powder and single crystal X-ray structural data including an assessment of the crystal packing and the void space in the crystalline space. The cyanide ligand and the R substituents are involved in hydrogen bonding that creates the voids within the structures and interact with the solvent molecules that influence the Pt⋯Pt separation in the crystalline state.

Here, a new tripodal tricarboxylic acid ligand, 4,4′-(4′-(4′-carboxy-[1,1′-biphenyl]-4-yl)-[2,2′:6′,2′′-terpyridine]-5,5′′-diyl)-dibenzoic acid (H3cbt), was synthesised using a three-step convergent strategy. Subsequent reactions with zinc(ii) nitrate hexahydrate yielded three metal-organic frameworks (MOFs). The three MOFs, [Zn(Hcbt)]·4DMF (1), [Zn(Hcbt)]·4DMSO·1.5H2O·DMF (2), and [Zn(Hcbt)]·2DMF·3H2O (3), each adopt flexible interdigitated 2D net topologies. Framework 1 has DMF-filled channels that retain porosity upon desolvation, with a measured BET surface area of 248 m2 g-1. Framework 2 possesses larger DMSO-containing channels that collapse upon desolvation, resulting in near-equivalent porosity values to framework 1. In silico calculations and topological considerations determined using the geometric simulation software GASP dictate that framework 2 can feasibly alter conformation to approximate 1, but cannot perfectly replicate the interdigitated motif. Framework 3 formed when wet solvents were used to synthesise 1. Interestingly, the interdigitated structure of 3 contains a unique carboxylate binding mode that precludes its subsequent adoption by either 1 or 2 upon their exposure to water. This diverse array of structural considerations recommends this MOF family for modelling using GASP. Interrogating frameworks 1-3 using this software provided insights that justified experimentally observed conformational trends, as well as barriers to interconversion between members of this MOF family. In a broader sense, this work demonstrates the wider applicability of GASP software to modelling structural changes within flexible MOF materials.

A series of mono-, di-, and poly(platina-ynes) incorporating stilbene spacer units with the formulae trans-[R–CC–Pt(PBu3)2-CC–R] (R = (E)-1,2-diphenylethene), trans-[(Ph)-(Et3P)2PtCC–R–CCPt(PEt3)2(Ph)] (R = (E)-1,2-diphenylethene), and trans-[–(PnBu3)2PtCC–R–CC–]n (R = (E)-1,2-diphenylethene), respectively, have been synthesized and characterized to explore the effects of ligand topology on the photoisomerization and photophysical properties of these materials. The structural and photophysical properties of the complexes have been investigated and compared with those of the previously reported mono-, di- and poly(platina-ynes) incorporating azobenzene spacers. We found that the organometallic species 1M, 2M and 1P undergo topology-dependent reversible trans-to-cis photoisomerization in CH2Cl2 solution. Computational modelling supported the experimental findings.

Pt(II) di-ynes and poly-ynes incorporating 5,5’- and 6,6’-disubstituted 2,2’-bipyridines were prepared following conventional Sonogashira and Hagihara dehydrohalogenation reaction protocols. Using Pt(II) dimers and polymers as a rigid-rod backbone, four new hetero-bimetallic compounds incorporating Re(CO)3Cl as a pendant functionality in the 2,2’-bipyridine core were obtained. The new hetero-bimetallic Pt-Re compounds were characterized by analytical and spectroscopic techniques. The solid state structures of a Re(I)-coordinated diterminal alkynyl ligand and a representative model compound were determined by single-crystal X-ray diffraction. Detailed photo-physical characterization of the hetero-bimetallic Pt(II) di-ynes and poly-ynes was carried out. We find that the incorporation of the Re(CO)3Cl pendant functionality in the 2,2’-bipyridine-containing main-chain Pt(II) di-ynes and poly-ynes has a synergistic effect on the optical properties, red shifting the absorption profile and introducing strong long-wavelength absorptions. The Re(I) moiety also introduces strong emission into the monomeric Pt(II) di-yne compounds, whereas this is suppressed in the poly-ynes. The extent of the synergy depends on the topology of the ligands. Computational modelling was performed to compare the energetic stabilities of the positional isomers and to understand the microscopic origin of the major optical absorptions. We find that 5,5’-disubstituted 2,2’-bipyridine systems are better candidates in terms of yield, photophysical properties and stability than their 6,6’-substituted counterparts. Overall, this work provides an additional synthetic route to control the photo-physical properties of metalla-ynes for a variety of optoelectronic applications.

We report the structural, spectroscopic, and computational studies of two new Re(I) tricarbonyl complexes bearing 2,3,6,7-tetraphenyl-1,4,5,8-tetraazaphenanthrene (Ph4TAP) and 4,5-diazafluoren-9-one (dafone) having a coordinated perrhenate group obtained via in situ superoxidation of Re(I) to Re(VII); intramolecular and intermolecular n → π* interactions are dominant and stabilize the molecular geometry and crystal packing.

Presently, there is little clarity concerning how organic additives control structure formation in the synthesis of zeolite catalysts. Such ambiguity is a major obstacle towards synthesis design of new bespoke zeolites with intended applications. Herein, we have applied inelastic neutron scattering (INS) spectroscopy to experimentally probe the nature of organic-framework interactions, which are crucial in understanding structure direction. With this technique we have studied the dynamics of 18-crown-6 ether, which can be used as an additive to direct the formation of four zeolites: Na-X, EMC-2, RHO and ZK-5. We observed significant softening of the 18-crown-6 ether molecule's dynamics upon occlusion within a zeolite host, with a strong influence on both the circular and radial vibrational modes. Furthermore, there is a strong correlation between the size/geometry of the zeolite framework cages and perturbations in the dynamics of the 18C6 oxyethylene chain. We propose that the approach used herein can be used to study other zeolites, and hence gain a more comprehensive view of organic-framework interactions.

The photophysical properties of two previously synthesized, highly efficient, bright red emitting complexes [Eu(btfa)3DPEPO] (CIE, 0.672; 0.326) (Eu-1) and [Eu(nta)3DPEPO] (CIE, 0.673; 0.326) (Eu-2) (btfa = 4,4,4-trifluoro-1-phenyl-1,3-butanedione, nta = 4,4,4-trifluoro-1-(2-naphthyl)-1,3-butanedione and DPEPO = bis(2-(diphenylphosphino)phenyl)ether oxide) are reported. The complexes have been used as dopants to fabricate several single and double emitting layer (EML) electroluminescent (EL) devices. At the optimum doping concentration of 4 wt%, the single EML device of Eu-1 exhibited a pure red color with an external quantum efficiency (EQE) of 2.9% and a maximum brightness (B) = 1320 cd m−2, maximum current efficiency (ηc) = 4.08 cd A−1, maximum power efficiency (ηp) = 3.37 lm W−1 with a very low turn-on voltage (Vturn-on) = 3.8 V. Importantly, the single EML device of Eu-2 at the optimum doping concentration exhibited pure red EL with EQE of 6.0% with the best EL performance: B = 2108 cd m−2, ηc = 8.45 cd A−1, and ηp = 6.98 lm W−1 at a very low Vturn-on = 3.5 V. The performances of this device are among the best reported for devices incorporating a europium complex as a red emitter. Furthermore, the EL performances were achieved at the current density of 10 mA cm−2, thereby alleviating a serious efficiency roll-off as a major obstacle to the development of Eu-complex based EL devices.

A new homodinuclear complex [Eu(btfa)3]2bpm (1) was synthesized incorporating 4,4,4-trifluoro-1-phenyl-1,3-butanedione (btfa) as the primary and 2,2′-bipyrimidine (bpm) as the auxiliary ligand. The complex was characterized by analytical and spectroscopic techniques, with special emphasis on the crystal structure and photoluminescence (PL) properties, both experimentally and theoretically. Single crystal X-ray diffraction (SCXRD) analysis reveals that the two Eu(III) ions in 1 are eight coordinate, where the bpm behaves as a N4 donor linking the two Eu(III) ions symmetrically. Each Eu(III) ion displays a distorted square antiprismatic (DSAP, D4d) coordination geometry. Complex 1 displayed bright red emission with (CIE)x,y color coordinates = 0.670; 0.330 and an absolute photoluminescence quantum yield (PLQY) of 54.4%. The theoretical intensity parameters (Ω2 and Ω4), radiative (AR) and non-radiative (ANR) decay rates, intrinsic quantum yield (QEuEu), sensitization efficiency (ηsen) and PLQY were assessed using the LUMPAC software and showed very good agreement with the experimental values. Based on these, an energy transfer (ET) mechanism is proposed and discussed. Moreover, 1 was used as an emitter to fabricate single- and double-emitting layer (EML) red-emitting electroluminescent devices. Double-EML device at the optimum doping concentration of 4.0 wt% displayed impressive EL performances, brightness (B) = 812 cd m−2, maximum current efficiency (ηc) = 3.97 cd A−1, maximum power efficiency (ηp) = 3.89 lm W−1, and external quantum efficiency (EQE) = 2.8% at very low Vturn-on = 3.2 V with (CIE)x,y = 0.662, 0.321 which is close to the standard red color recommended by NTSC (0.67, 0.33).

A new samarium complex [Sm(hfaa)3(Py-Im)] (ML) was synthesized by utilizing hexafluoroacetylacetone (hfaa) and 2-(2-pyridyl)benzimidazole (Py-Im) as coordinating ligands. Single crystal X-ray analysis shows that in the solid-state the complex dimerizes through intermolecular hydrogen-bonding with N-H?O (2.127 Å) and N-H?F (2.576 Å) interactions. The complex in the solid-state displayed highly monochromatic brilliant red emission with Commission International de I'Eclairage (CIE) color coordinates of 0.6532; 0.3336, with a remarkably long luminescence lifetime (?exp. ? 204.47 ± 4.043 ?s) and a high intrinsic quantum yield (QSmSm ? 6.60%). Furthermore, the complex in different organic media displayed color tunability from orange (CIE; 0.6071; 0.3568) to violet (CIE; 0.3634; 0.2144) with ?exp. from 105.50 ± 0.143 to 14.27 ± 0.033 ?s. Hybrid and flexible thin films obtained by doping different concentrations (1%, 2%, 4% and 6%) of the complex into the poly(urethane) (PU) polymer matrix also exhibited color tunability from violet (CIE; 0.3380; 0.2162) to light orange (CIE; 0.5666; 0.3408). White light emission from a 1% doped thin film of the complex was realized by changing the excitation wavelength. Thus, the new material could be a potential candidate for the fabrication of full-color display devices and for solid-state lighting (SSL) applications. This journal is © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique. F.279 Engineering and Physical Sciences Research Council: EP/K004956/1 SR/SQU/SCI/CHEM/16/02 MSK acknowledges His Majesty’s Trust Fund for Strategic Research (Grant No. SR/SQU/SCI/CHEM/16/02) for funding. RI thanks the HM’s Trust Fund for a post-doctoral fellowship. The authors acknowledge the Faculty of Arts and Sciences, Ondokuz Mayıs University, Turkey, for the use of the Stoe IPDS 2 diffractometer (purchased under grant F.279 of the University Research Fund). PRR is grateful to the Engineering and Physical Sciences Research Council (EPSRC) for continued support (Grant EP/K004956/1).

Two new octa-coordinated ternary europium(III) complexes of the type [Eu(btfa)3(Br2-bpy)] (Eu-1) and [Eu(btfa)3(PhE2-bpy)] (Eu-2) (where btfa = 4,4,4-trifluoro-1-phenyl-1,3-butanedione, Br2-bpy = 5,5′-dibromo-2,2′-bipyridine, PhE2-bpy 5,5′-bis(phenylethynyl)-2,2′-bipyridine) together with a previously reported complex [Eu(btfa)3(bpy)] (Eu-3) have been synthesized. The complexes have been characterized by analytical and spectroscopic methods. The photophysical properties of the complexes have also been analyzed both experimentally and theoretically. The contribution of each ligand to the sensitized Eu(III) photoluminescence (PL) has been analyzed and is discussed. An energy transfer (ET) mechanism is proposed and discussed for the sensitized Eu(III) emission using experimental and theoretical data. The Eu(III) complex incorporating the parent bpy showed impressive performance as a double-emitting layer (EML) red organic light emitting diodes (R-OLEDs).

A series of tetrakis lanthanide complexes with the general formula [Ln(hfaa) 4] -(DpaH) + [Ln = (Sm-1), (Eu-1) and (Tb-1)], hfaa = hexafluroacetylacetonate and Dpa −2,2′-dipyridylamine] has been synthesized by the reaction of LnCl 3, hfaa and Dpa in the presence of ammonia solution (25%). The complexes have been characterized by analytical and spectroscopic methods. The solution molecular structure of the complexes was elucidated by one- and two-dimensional NMR spectroscopy which shows that the DpaH + cation retains a close interaction with the lanthanide anion in solution. The crystal structure of Eu-1, determined by single crystal X-ray diffraction, confirms this intermolecular interaction in the solid-state through a N–H⋯O hydrogen bond of 2.187 Å. In the [Eu(hfaa) 4] - anion the EuO 8 coordination polyhedron has a distorted triangular dodecahedron geometry with approximate D 2d-symmetry around the metal centre. Photophysical, thermal, and electroluminescent properties of the complexes have been investigated. The Sm-1 and Eu-1 complexes displayed efficient typical red emission with a sizeable photoluminescence quantum yield (PLQY) while Tb-1 displayed near-white light emission. The complexes have been used as dopants to fabricate single- and double-emitting layer (EML) OLEDs through the thermal evaporation method. At the optimum doping concentration, double-EML Eu-1 based device displayed orange electroluminescence (EL) with a brightness (B) of 417 cd/m 2 and very low V turn-on = 3.4 V. Interestingly, the Sm-1 based single-EML device exhibited pure red emission with the Commission internationale de l'éclairage [(CIE) x,y = 0.613, 0.321], which is rare. The Sm-1 based device performance [B = 145 cd/m 2, current efficiency (η c) = 0.35 cd/A, power efficiency (η p) = 0.15 lm/W with an external quantum efficiency (EQE) = 0.3% and V turn-on = 7.1 V] surpassed that of the only reported Sm-based single red-OLED (R-OLED).

Advances in synthetic chemistry mean that the molecules now synthesized include increasingly complex entities with mechanical bonds or extensive frameworks. For these complex molecular and supramolecular species, single-crystal X-ray crystallography has proved to be the optimal technique for determining full three-dimensional structures in the solid state. These structures are curated and placed in structural databases, the most comprehensive of which (for organic and metallo–organic structures) is the Cambridge Structural Database. A question of increasing importance is how users can search such databases effectively for these structures. Here some of the classes of complex molecules and supramolecules and the challenges associated with searching for them are highlighted. The idea of substructure searches that involve topological searches as well as searches for molecular fragments is developed, and significant enhancements are proposed to substructure search programs that are both achievable and highly beneficial for both the database user community and the broader chemistry community.

Two new mixed ligand complexes [Eu(tfac)3(DPEPO)] (Eu-1) and [Tb(tfac)3(DPEPO)] (Tb-2) incorporating trifluoroacetylacetone (Htfac) and bis(2-(diphenylphosphino)phenyl)ether oxide (DPEPO) were synthesized in gram-scale quantities and used as emitters to fabricate single- and double-EML (light-emitting layer) electroluminescence (EL) devices. The single-EML device with the structure: ITO/HAT-CN (6 nm)/HAT-CN (0.2 wt%):TAPC (50 nm)/Eu-1 (1–6 wt%): 26DCzPPy (10 nm)/Tm3PyP26PyB (50 nm)/LiF (1 nm)/Al (100 nm) showed light red (CIE, x: 0.574; y: 0.275) emission for the Eu-1 based EL devices due to the presence of a host emission with a brightness of 1274 cd m−2, current efficiency (ηc), power efficiency (ηp) and external quantum efficiency (EQE) of 0.58 cd A−1, 0.68 lm W−1, and 0.70%, respectively. The single-EML device for the Tb-2 complex with the same device structure displayed white-light emission. The optimized single-EML device of Tb-2 with 14.0 wt% doping concentration showed an impressive EL performance with brightness of 1637 cd m−2, ηc ≈ 3.05 cd A−1, ηp ≈ 2.80 lm W−1, EQE ≈ 1.4%, Vturn-on ≈ 3.1 V, respectively. This is the first report of single component white organic light emitting diode (W-OLED) fabricated from an organo-Tb(III) complex. The W-OLEDs show low turn-on voltages (Vturn-on) ≈ 3.1 V and are thus advantageous in lowering the power consumption of the OLED display.

Two unique series of lanthanide complexes [Ln(Ph3PO)4(NCS)3] (Ln = La-Tb, except Pm) and [Ln(Ph3PO)3(NCS)3] (Ln = Sm-Lu, Y) have been structurally characterised. The isomorphous series [Ln(Ph3PO)4(NCS)3] crystallises in the monoclinic centrosymmetric space group P21/c, and the metals display a capped octahedral coordination geometry. In contrast, the isomorphous series [Ln(Ph3PO)3(NCS)3] (Ln = Sm-Lu, Y) crystallise in the non-centrosymmetric space group R3, with the metal displaying an octahedral coordination geometry; the fac-isomer being observed in all cases. Intriguingly, for the metals Sm-Tb both the seven and six coordinate complexes can be isolated from the respective synthetic routes suggesting a structural equilibrium in solution. An analysis of the distortions of the ligand polyhedron in the two series using the continuous shape measurement (CShMs) method suggests trends across the series relating to the fit of the ligands with the size of the lanthanide ions.

We present the synthesis and characterization of seven new organic co-poly-ynes P1-P7 incorporating the phenothiazine (PTZ) motif and evaluate their optoelectronic properties and performance in polymer light-emitting diodes and polymer solar cells (PLEDs/PSCs). The co-poly-ynes were obtained in moderate to high yields via Sonogashira coupling reactions and characterized using analytical, spectroscopic and electrochemical techniques and complementary quantum-chemical modelling. The materials show strong optical absorption in the visible region of the spectrum and most also show strong emission with quantum yields in the range of 13-41% relative to rhodamine 6G (R6G). PLED devices based on the co-poly-ynes were prepared and the most promising was measured to have a brightness of up to 1.10 × 104 cd m-2. PSCs based on donor materials incorporating some of the polymers were prepared and demonstrated power conversion efficiencies of up to 0.24%. This journal is

For a range of organic solvents, the likelihood of the solvent forming solvates has been estimated using the recrystallization solvent (RS) data in the Cambridge Structural Database (CSD). Although RS data are viewed with caution by some crystallographers, most of the likelihood estimates are shown to have good precision. Strong trends are apparent in the results. For example, high likelihoods are found for aromatic solvents with electron-withdrawing substituents and low likelihoods for acyclic aliphatic hydrocarbons. Results for different CSD subsets, such as organic and metalloorganic, are highly correlated. The likelihood that a solvent will form solvates is almost always higher when the solvent is part of a mixture than when it is pure. The likelihood of two solvents forming a heterosolvate (i.e., both solvents in the structure) can be well estimated by the product of the likelihoods of the solvents forming normal solvates (i.e., only one solvent in the structure). The space-group preferences of solvates vary significantly with the nature of the cocrystallized solvent. Those of nonsolvates vary significantly with the solvent(s) from which they were crystallized. Solvents with inversion centers favor solvate crystallization in centrosymmetric space groups, and solvents with 2-fold rotational symmetry promote crystallization in space groups with 2-fold proper rotational axes. The inclusion of cyclohexane and carbon tetrachloride in a lattice can facilitate crystallization in trigonal and tetragonal space groups, respectively. Our results can: (a) guide solvent selection when solvates are undesired; (b) assist in predicting solvate formation, e.g., using Bayesian algorithms; (c) assist in the choice of space groups for solvate crystal structure prediction; and (d) suggest ways in which solvent incorporation can be used to influence space groups.

The title compound, [Cu4Cl6O(C13H9N)4], was obtained by the reaction of CuCl with 4-phenyl­ethynyl­pyridine in di­chloro­methane. The complex contains a tetra­hedron of four CuII cations coordinated to a central μ4-O atom, with the six edges of the Cu4 tetra­hedron bridged by Cl atoms. The Cu—O distances average 1.905 Å and Cu—Cl 2.418 Å., In the crystal structure of the title compound, [Cu4Cl6O(C13H9N)4]·CH2Cl2, the core mol­ecular structure consists of a Cu4 tetra­hedron with a central inter­stitial O atom. Each edge of the Cu4 tetra­hedron is bridged by a chlorido ligand. Each copper(II) cation is coordinated to the central O atom, two chlorido ligands and one N atom of the 4-phenyl­ethynyl­pyridine ligand. In the crystal, the mol­ecules are linked by inter­molecular C—H⋯Cl inter­actions. Furthermore, C—H⋯π and π–π inter­actions also connect the mol­ecules, forming a three-dimensional network. Hirshfeld surface analysis indicates that the most important contributions for the packing arrangement are from H⋯H and C⋯H/H⋯C inter­actions.

A new heterotrinuclear (d-f-d) complex [Eu(btfa)31c] (btfa = 4,4,4-trifluoro-1-phenyl-1,3-butanedione and 1c = [(Ph)(Et3P)2Pt-C[triple bond, length as m-dash]C-R-C[triple bond, length as m-dash]C-Pt(Et3P)2(Ph)] (R = 2,2'-bipyridine-5,5'-diyl) has been synthesized by utilizing the N,N-donor sites of the organometallic chromophore. The complex was characterized by analytical and spectroscopic methods. Photophysical properties of the complex were analysed in detail using both steady-state and time-resolved emission and excitation spectroscopy. The optical absorption spectrum of the complex is dominated by the spin allowed π-π* transitions of the btfa and 1c units in the UV-visible region (200-418 nm) and thus is excitable over a wide range of wavelengths across the UV into the visible region of the electromagnetic spectrum. The complex displays typical red Eu(iii) emission when excited at 345 nm. However, it also shows green emission when excited at 464 nm and, thus could be an interesting candidate for full colour display applications. The change in the colour could be a result of the high value of the energy back-transfer rate (6.73 × 105 s-1) from the triplet state of the organometallic chromophore to the 5D1 state of Eu(iii). Judd-Ofelt (J-O) intensity parameters (Ω2 and Ω4), radiative (AR), non-radiative (AR) decay rates and intrinsic quantum yield (Q) have been calculated.

A simple yet efficient instrument-model refinement method for X-ray diffraction data is presented and discussed. The method is based on least-squares minimization of differences between respective normalized (i.e. unit length) reciprocal vectors computed for adjacent frames. The approach was primarily designed to work with synchrotron X-ray Laue diffraction data collected for small-molecule single-crystal samples. The method has been shown to work well on both simulated and experimental data. Tests performed on simulated data sets for small-molecule and protein crystals confirmed the validity of the proposed instrument-model refinement approach. Finally, examination of data sets collected at both BioCARS 14-ID-B (Advanced Photon Source) and ID09 (European Synchrotron Radiation Facility) beamlines indicated that the approach is capable of retrieving goniometer parameters (e.g. detector distance or primary X-ray beam centre) reliably, even when their initial estimates are rather inaccurate.\udKeywords: data processing; Laue diffraction; instrument models; refinement; X-ray diffraction.

The authors gratefully acknowledge support from an EPSRC programme grant (grant no. EP/K004956/1). Manipulating the emission characteristics of phosphors is a viable strategy to produce unique, and thus difficult to replicate, security optical features that are useful in anticounterfeiting applications. Here, a fluorophore, BODIPY 493/503, displayed altered solid-state emission characteristics upon being hosted within a crystalline molecular flask. Specifically, a bathochromic shift of 939 cm-1 was observed (λ(max): 633 → 673 nm), with a concomitant reduction in emission intensity, and emission dependency on excitation wavelength. Multiple factors likely contribute to this behaviour, such as emission filtering by the host framework, exciplex formation between BODIPY and the electron-deficient framework, and collisional quenching between the host and guest. Here we prioritize solid-state analyses to explore these factors, including electron density mapping of the framework pores, and multinuclear solid-state NMR spectroscopy. Publisher PDF

Boron-containing π-conjugated materials are archetypical candidates for a variety of molecular scale applications. The incorporation of boron into the π-conjugated frameworks significantly modifies the nature of the parent π-conjugated systems. Several novel boron-bridged π-conjugated materials with intriguing structural, photo-physical and electrochemical properties have been reported over the last few years. In this paper, we review the properties and multi-dimensional applications of the boron-bridged fused-ring π-conjugated systems. We critically highlight the properties of π-conjugated N^C-chelate organoboron materials. This is followed by a discussion on the potential applications of the new materials in opto-electronics (O-E) and other areas. Finally, attempts will be made to predict the future direction/outlook for this class of materials.

In this chapter the development of time-resolved crystallography is traced from its beginnings more than 30 years ago. The importance of being able to “watch” chemical processes as they occur rather than just being limited to three-dimensional pictures of the reactant and final product is emphasised, and time-resolved crystallography provides the opportunity to bring the dimension of time into the crystallographic experiment. The technique has evolved in time with developments in technology: synchrotron radiation, cryoscopic techniques, tuneable lasers, increased computing power and vastly improved X-ray detectors. The shorter the lifetime of the species being studied, the more complex is the experiment. The chapter focusses on the results of solid-state reactions that are activated by light, since this process does not require the addition of a reagent to the crystalline material and the single-crystalline nature of the solid may be preserved. Because of this photoactivation, time-resolved crystallography is often described as “photocrystallography”. The initial photocrystallographic studies were carried out on molecular complexes that either underwent irreversible photoactivated processes where the conversion took hours or days. Structural snapshots were taken during the process. Materials that achieved a metastable state under photoactivation and the excited (metastable) state had a long enough lifetime for the data from the crystal to be collected and the structure solved. For systems with shorter lifetimes, the first time-resolved results were obtained for macromolecular structures, where pulsed lasers were used to pump up the short lifetime excited state species and their structures were probed by using synchronised X-ray pulses from a high-intensity source. Developments in molecular crystallography soon followed, initially with monochromatic X-ray radiation, and pump-probe techniques were used to establish the structures of photoactivated molecules with lifetimes in the micro- to millisecond range. For molecules with even shorter lifetimes in the sub-microsecond range, Laue diffraction methods (rather than using monochromatic radiation) were employed to speed up the data collections and reduce crystal damage. Future developments in time-resolved crystallography are likely to involve the use of XFELs to complete “single-shot” time-resolved diffraction studies that are already proving successful in the macromolecular crystallographic field.

Data deposited in the Cambridge Structural Database (CSD) for compounds of scandium, yttrium, lanthanum and lutetium(III) have been analysed to assess the structural similarities of complexes of the different metal ions. 29 sets of compounds of Sc, Y, La and Lu where at least three of the elements form compounds with the same ligands have been identified and their crystal structures analysed. In 14 of them, scandium and lutetium have the same coordination number; in the remaining 15 they do not. Similarly, there are 10 examples where there is a difference in coordination number between Lu and Y for compounds with the same ligands. For the other 19 either the coordination numbers are the same or that compounds for both the elements under consideration have not been reported. Overall structural differences correlate well with the size of the metal ions and provide no true chemical basis for arranging Lu rather than La in one triad with Sc and Y.

This paper demonstrates the potential of vapochromic crystals as a sensing medium for measurements of local species concentration. Vapochromic crystals exhibit a reversible colour change based on the adsorption and desorption of water. As the water content of the crystals changes so too does the wavelength of light that they reflect (i.e. they change colour). In the situation where humid air mixes with a dry gas, the resulting specific humidity of the mixture can be related to the concentration level of the dry gas through a simple mass balance. As far as the authors are aware, this is the first time that vapochromic crystals have been used in this context. A number of the factors that affect the colour change of the crystal are investigated through simple flat plate experiments in a small wind tunnel. In all experiments, the hue and intensity of the vapochromic crystal was measured as a function of local dry gas concentration; in this case CO2. Green intensity levels exhibited the broadest activity over the widest range of CO2 levels, and was therefore used to quantify concentration. The crystals demonstrated a pronounced hysteresis, where the adsorption and desorption of water into the crystal structure was shown to occur at different concentration levels. The transition band was also shown to be highly temperature dependent when tested over a range of 22–44 °C. The vapochromic crystals were assessed for repeatability and found to sense the local CO2 concentration to ±1.5% CO2 over a range of green intensity values from 90 to 170. A practical example is presented to show how vapochromic crystals could be applied to the mixing of fluid streams in gas turbine film cooling.

Heteroaryl incorporated acetylide-functionalized pyridinyl ligands (L1-L6) with the general formula Py-C≡C-Ar (Py = pyridine and Ar = thiophene-2-yl, 2,2' -bithiophene]-5-yl, 2,2' :5',2″ -terthiophene]-5-yl, thieno[2,3- b]thiophen-2-yl, quinoline-5-yl, benzo[c][1,2,5]thiadiazole-5-yl) have been synthesized by Pd(0)/Cu(I)-catalyzed cross-coupling reaction of 4-ethynylpyridine and the respective heteroaryl halide. Ligands L1-L6 were isolated in respectable yields and characterized by microanalysis, IR spectroscopy, 1H NMR spectroscopy, and ESI-MS mass spectrometry. A series of dinuclear Cu(I) complexes 1-10 have been synthesized by reacting L1-L6 with CuI and triphenylphosphine (PPh3) (R1) or with an anchored phosphine derivative, 4-(diphenylphosphino) benzoic acid (R2)/2-(diphenylphosphino)benzenesulfonic acid (R3), in a stoichiometric ratio. The complexes are soluble in common organic solvents and have been characterized by analytical, spectroscopic, and computational methods. Single-crystal X-ray structure analysis confirmed rhomboid dimeric structures for complexes 1, 2, 4, and 5, and a polymeric structure for 6. Complexes 1-6 showed oxidation potential responses close to 0.9 V vs Fc0/+, which were chemically irreversible and are likely to be associated with multiple steps and core oxidation. Preliminary photovoltaic (PV) results of these new materials indicated moderate power conversion efficiency (PCE) in the range of 0.15-1.56% in dye-sensitized solar cells (DSSCs). The highest PCE was achieved with complex 10 bearing the sulfonic acid anchoring functionality.

An unusual heterobimetallic bis(triphenylphosphane)(NO2)AgI–CoIII(dimethylglyoximate)(NO2) coordination compound with both bridging and terminal –NO2 (nitro) coordination modes has been isolated and characterized from the reaction of [CoCl(DMGH)2(PPh3)] (DMGH2 is dimethylglyoxime or N,N′-dihydroxybutane-2,3-diimine) with excess AgNO2. In the title compound, namely bis(dimethylglyoximato-1κ2 O,O′)(μ-nitro-1κN:2κ2 O,O′)(nitro-1κN)bis(triphenylphosphane-2κP)cobalt(III)silver(I), [AgCo(C4H7N2O2)2(NO2)2(C18H15P)2], one of the ambidentate –NO2 ligands, in a bridging mode, chelates the AgI atom in an isobidentate κ2 O,O′-manner and its N atom is coordinated to the CoIII atom. The other –NO2 ligand is terminally κN-coordinated to the CoIII atom. The structure has been fully characterized by X-ray crystallography and spectroscopic methods. Density functional theory (DFT) and time-dependent density functional theory (TD-DFT) have been used to study the ground-state electronic structure and elucidate the origin of the electronic transitions, respectively.

We report two hitherto unknown polymorphs of the charge transfer (CT) cocrystal perylene:tetracyanoquinodimethane (TCNQ) grown by physical vapor transport (PVT) in argon atmosphere. One of the polymorphs, named β, has stoichiometry 1:1 and adds to the three known structures with stoichiometry 1:1 (α), 2:1, and 3:1. Interestingly, below (280 ± 10) K the β structure undergoes a phase transition to what we refer to as the γ polymorph, with halving of the unit cell and reduction of symmetry from monoclinic to triclinic. Both new crystal structures present two alternating stacks with different intermolecular and intramolecular geometries. In stack S–I the perylene molecules show substantial deviations from planarity, with the angle between the naphthalene intramolecular moieties of 6.69°, and with the perylene and TCNQ molecular centroids shifted by 1.95 Å. In the second stack, S-II, the perylene is planar, and the centroids almost coincident. Structural investigations on bond length complemented by vibrational IR spectroscopy indicate that in the new polymorphs the degree of charge transfer, ρ, can be 0 or 0.12. The higher value of ionicity to be due to donor–acceptor pairs in the S-II, while molecules in S-I are closer to neutrality. Thus, the ionicity of the donor–acceptor pair depends on the stack and is comparable to that of the α polymorph which we redetermined as ρ = 0.15 ± 0.05.

Presently it is understood that 18-crown-6 ether is necessary as an organic template to synthesise pure and well crystalline EMT-type zeolites. This is problematic for optimisation of organic-free synthesis of zeolites. We report a new method to synthesise pure zeolite EMC-2 using a lower amount of 18-crown-6 ether than previously reported. At these low 18-crown-6 ether concentrations, FAU-type zeolites were not seen to co-crystallise. We observe that the crystallinity of the EMT-type zeolite is proportional to the amount of 18-crown-6 ether added in the synthesis. The as-synthesised zeolites were characterised using X-ray powder diffraction, scanning electron microscopy and solid state nuclear magnetic resonance. These findings are a crucial step towards understanding template roles and designing syntheses for zeolites without the use of toxic organic templates.

Reaction of the electron-rich complex cis-[Pt(p-Me-C6H4)2(SMe2)2] with 2,2′-bipyridine N-oxide, O-bpy occurred by rollover cyclometalation to afford complex [Pt(O-bpy)(p-Me-C6H4)(SMe2)], 1. The obtained complex was characterized using NMR spectroscopy and its solid state structure was determined by the single crystal X-ray diffraction method. The reaction of 1 with seven diphosphine ligands, 1,1-bis(diphenylphosphino)methane (dppm), 1,2-bis(diphenylphosphino)ethane (dppe), 1,3-bis(diphenylphosphino)propane (dppp), 1,4-bis(diphenylphosphino)butane (dppb), N,N-bis(diphenylphosphino)amine (dppa), 1,2-bis(diphenylphosphino)benzene (dppbz) and 1,1′-bis(diphenylphosphino)ferrocene (dppf), in different molar ratios (1:1 or 1:0.5; 1:diphosphines) was studied. In accordance with the reaction conditions, the analogous mononuclear or binuclear diphosphine cycloplatinated complexes were yielded. The diphosphines behave as a monodentate (dppm and dppa), a bridging (dppm, dppa, dppe, dppp, dppb and dppf) or a chelated (dppe, dppp and dppbz) ligand. These behaviors depend on the bite angle of the diphosphine ligands, and the flexibility or rigidity of the alkyl and aromatic backbone between the two phosphine groups. All diphosphine platinum complexes were characterized using NMR spectroscopy and the crystal structures of some complexes were solved by X-ray diffraction.

[Ru3(CO)12] reacts at room temperature with N-alkyl substituted 6-membered ring N-heterocyclic carbenes (6-NHC) to form [Ru3(6-NHC)(CO)10] (6-NHC = 6-iPr 1, 6-Et 2 and 6-Me 4), rare examples of coordinatively unsaturated (46-electron) ruthenium clusters. Complexes 1, 2 and 4 have been structurally characterised, along with the tetranuclear ruthenium cluster [Ru4(6-Et)2(CO)11] 3 that is formed along with 2. The degradation of the 6-iPr derivative 1 by pyrimidinium salt elimination helped to explain the poor activity of the complex in the catalytic acylation of pyridine.

A new tris β-diketonate europium(III) complex [Eu(btfa)3Py-Im] (Eu-1) (4,4,4-trifluoro-1-phenyl-1,3-butanedione (btfa) and 2-(2-pyridyl)benzimidazole (Py-Im)] has been synthesized and structurally characterized. A single crystal X-ray diffraction analysis shows that Eu-1 is octacoordinated and the coordination sphere is composed of a EuO6N2 core with a trigonal dodecahedral (D2d) geometry. The photophysical properties of Eu-1 were analysed in detail and with the help of the experimental PL data and theoretical modelling, energy transfer rates were calculated, and an energy transfer mechanism is proposed for Eu-1. The complex has been used as the emitting layer (EML) to fabricate organic light emitting diodes (OLEDs). Eight OLEDs, of which four single-EML and four double-EML with varying doping concentration, were fabricated via a thermal evaporation method using Eu-1 as the EML. Under the optimum conditions a highly monochromatic bright red emission (CIEx,y = 0.640, 0.311) with brightness (B) = 896 cd/m2, current efficiency (ηc) = 2.26 cd/A, power efficiency (ηp) = 1.92 lm/W and external quantum efficiency (EQE) = 1.6% at very low Vturn-on = 3.4 V was obtained.

A ligand field molecular mechanics (LFMM) force field has been constructed for the spin states of [Fe(bpp)2 ]2+ (bpp=2,6-di(pyrazol-1-yl)pyridine) and related complexes. A new charge scheme is employed which interpolates between partial charges for neutral bpp and protonated [H3 bpp]3+ to achieve a target metal charge. The LFMM angular overlap model (AOM) parameters are fitted to fully ab initio d orbital energies. However, several AOM parameter sets are possible. The ambiguity is resolved by calculating the Jahn-Teller distortion mode for high spin, which indicates that in [Fe(bpp)2 ]2+ pyridine is a π-acceptor and pyrazole a weak π-donor. The alternative fit, assumed previously, where both ligands act as π-donors leads to an inconsistent distortion. LFMM optimisations in the presence of [BF4 ]- or [PF6 ]- anions are in good agreement with experiment and the model also correctly predicts the spin state energetics for 3-pyrazolyl substituents where the interactions are mainly steric. However, for 4-pyridyl or 4-pyrazolyl substituents, LFMM only treats the electrostatic contribution which, for the pyridyl substituents, generates a fair correlation with the spin crossover transition temperatures, T1/2 , but in the reverse sense to the dominant electronic effect. Thus, LFMM generates its smallest spin state energy difference for the substituent with the highest T1/2 . One parameter set for all substituted bpp ligands is insufficient and further LFMM development will be required.

Four novel ON donor Schiff bases (E)-3-((4-phenoxyphenylimino)methyl)benzene-1,2-diol (HL1),(E)-3-((4-(4-biphenyloxy)phenyliminomethyl)benzene-1,2-diol (HL2), (E)-3-((4-naphthoxyphenylimino)methyl)benzene-1,2-diol (HL3), (E)-3-((4-(2-naphthoxy)phenylimino)methyl)benzene-1,2-diol (HL4) and their copper(II) complexes bis((E)-3-((4-phenoxyphenylimino)methyl)benzene-1,2-diol) copper(II) (Cu(L1)2) bis((E)-3-((4-(4-biphenyloxy)phenylimino)methyl)benzene-1,2-diol) copper(II) (Cu(L2)2), bis((E)-3-((4-naphthoxyphenylimino)methyl)benzene-1,2-diol) copper(II) (Cu(L3)2), bis((E)-3-((4-(2-naphthoxy)phenylimino)methyl)benzene-1,2-diol) copper(II) (Cu(L4)2) have been synthesized and characterized by spectroscopic (FTIR, NMR, UV–visible) and elemental analysis. The crystal structures of HL1, HL2, HL3, and HL4 have been determined, which reveal intramolecular N-H⋯O (HL1, HL2, HL3, and HL4) hydrogen bonds in the solid state. Keto-amine and enol-imine tautomerism is exhibited by the Schiff bases in solid and solution states. The Schiff bases and their copper(II) complexes have been screened for their biological activities. In antimicrobial assays (antibacterial and antifungal), HL4 showed promising results against all strains through dual inhibition property while the rest of the compounds showed activity against selective strains. On the other hand, in cytotoxic, DPPH, and inhibition of hydroxyl (OH) free radical-induced DNA damage assays, the results were found significantly correlated with each other, i.e. the ligands HL1 and HL2 showed moderate activity while their complexes Cu(L1)2 and Cu(L2)2 exhibited prominent increase in activity. As the results of these assays are supporting each other, it represents the strong positive correlation and antioxidant nature of investigated compounds.

Square planar platinum(ii) complexes have been known for 150 years and pincer complexes, supported by a tridentate chelating ligand such as terpyridyl, have been known for more than 70 years. The development of cyclometallated platinum(ii) pincer complexes, in which the tridentate ligand forms one or more platinum-carbon bonds, has been much more recent. Particularly, in terms of their solution and solid-state luminescence these cyclometallated complexes show substantial advantages over their terpyridyl analogues. This tutorial review introduces the reader to the area of platinum(ii) cyclometallated pincer chemistry and shows the advantage of having an alkynyl group in the fourth coordination site on the metal. The basic design principles for the preparation of highly luminescent platinum(ii) cyclometallated pincer complexes are outlined and the strategy to improve the luminescence further by chemical manipulation of the pincer ligand and of the auxiliary ligand in the fourth coordination site are illustrated with recent examples from the literature. Recent applications of these cyclometallated pincer complexes in the area of opto-electronics is described, with emphasis on their use in OLEDs, OFETs and as NLO materials as well as demonstrating their potential use as triplet photosensitizers and as metal ion sensors. The aim of this review is to show the recent advances in this rapidly developing research field and to highlight the future promise of these materials.

Presently there is little clarity concerning how organic additives control structure formation in the synthesis of zeolite catalysts and their chemistry. Such ambiguity is a major obstacle towards the synthesis design for new bespoke zeolites with intended applications. Herein, we have applied inelastic neutron scattering (INS) spectroscopy to experimentally probe the organic-framework interactions that are crucial to the structure direction process. With this technique we have studied the dynamics of 18-crown-6 ether, which can be used as an additive to direct the formation of four zeolites: Na-X, EMC-2, RHO and ZK-5. We observe significant softening of the 18-crown-6 ether molecule’s dynamics upon occlusion within a zeolite host, with a strong influence on both the circular and radial vibrational modes. Furthermore, there is a strong correlation between the efficacy of the organic additive and the strength of the organic-framework interactions, which are a consequence of both the framework cavity size and geometry. We propose that the approach used herein should be used to study other zeolites, and hence gain a more comprehensive view of structure directing organic-framework interactions.

A new zwitterionic Palladium (II) complex has been synthesized by the one-pot mixing of Pd(OAc)2, 2-aminophenol and (3-formyl-4-hydroxy-5-methylbenzyl) triphenylphosphonium chloride, in refluxing ethanol. The metal complex formed was characterized by 1H NMR, 13C NMR, 31P NMR and X-ray crystallographic technique and its efficiency tested as a homogeneous pre-catalyst in Heck-Mizoroki cross coupling reaction using γ-Valerolactone (GVL) as a biomass-derived green medium. All the products were obtained in good to excellent yields.