Regioisomerism in cationic sulfonyl-substituted [Ir(C^N)2(N^N)]+ complexes: its influence on photophysical properties and LEC performance

In a series of regioisomeric [Ir(C^N)₂(bpy)]⁺ complexes containing methylsulfonyl groups on the cyclometallating ligands, the influence of the substitution position on photophysical, electrochemical and LEC device properties is investigated.

Combining phosphonic acid-functionalized anchoring ligands with asymmetric ancillary ligands in bis(diimine)copper(i) dyes for dye-sensitized solar cells

A 6,6′-dimethyl substitution pattern in L_anchor in [Cu(L_anchor)(L_ancillary)]⁺ dyes in DSCs is superior to two phenyl groups, even when steric crowding is alleviated by using asymmetric L_ancillary.

Peripheral halo-functionalization in [Cu(N^N)(P^P)]+ emitters: influence on the performances of light-emitting electrochemical cells

Trends in the performance data of [Cu(N^N)(P^P)]⁺-based LECs in which N^N ligands bear peripheral F, Cl, Br or I substituents reveal that fluoro-groups are beneficial, but heavier halo-substituents lead to poor devices.

Improved light absorbance does not lead to better DSC performance: studies on a ruthenium porphyrin–terpyridine conjugate

Despite having a good spectral response, a bis(tpy)ruthenium complex with peripheral porphyrin and phosphonate anchoring domains gives poor photoconversion efficiency due to a triplet–triplet energy transfer process.

Understanding the formation of aligned, linear arrays of Ag nanoparticles

A self-assembly process, the Liesegang phenomenon, was applied to align silver nanoparticles in highly periodic linear arrays and two alternative mechanisms were proposed to explain the process.

Copper-based dye-sensitized solar cells with quasi-solid nano cellulose composite electrolytes

Compatability of copper(i) based dyes with quasi solid state electrolytes enhanced with cellulose nano crystals in DSSCs is demonstrated.

Cyanoacrylic- and (1-cyanovinyl)phosphonic acid anchoring ligands for application in copper-based dye-sensitized solar cells

Replacing phosphonic acid by (1-cyanovinyl)phosphonic acid anchors in heteroleptic bis(diimine)copper(i) dyes in DSCs gives a gain in J_SC; a dye with a bpy-based anchor gives improved performance over one with a phen-based anchor.

[Ir(C^N)2(N^N)]+ emitters containing a naphthalene unit within a linker between the two cyclometallating ligands

The effects of introducing a naphthalene unit between the two cyclometallating ligands in [Ir(C^N)₂(N^N)]⁺ emitters in LECS are explored.

[Cu(N^N)(P^P)]+ complexes with 2,2':6',2''-terpyridine ligands as the N^N domain

The first examples of [Cu(N^N)(POP)](+) complexes (POP = bis(2-(diphenylphosphino)phenyl)ether) in which the N^N domain is a 2,2':6',2''-terpyridine (tpy) ligand have been prepared and characterized; N^N = tpy, 5,5''-dimethyl-2,2':6',2''-terpyridine (1), 4′-(4-tolyl)-2,2′:6′,2′′-terpyridine (2), 4′-(4-npropoxyphenyl)-2,2′:6′,2′′-terpyridine (3) and 4′-(4-nbutoxyphenyl)-2,2′:6′,2′′-terpyridine (4). In solution, the tpy domain in each [Cu(N^N)(POP)][PF6] complex is C2-symmetric, consistent with either tridentate coordination or a low energy dynamic process involving bidentate ligands; for [Cu(2)(POP)][PF6] and [Cu(4)(POP)][PF6], the (1)H NMR spectra showed negligible change between 295 and 210 K. The single crystal structures of [Cu(tpy)(POP)][PF6] and [Cu(4)(POP)][PF6] are presented. The asymmetric unit of [Cu(tpy)(POP)][PF6] contains two independent cations; in one the tpy ligand is tridentate and in the other, it is bidentate with the non-coordinated pyridine ring facing the Cu atom (Cu···N = 3.146(1) Å). In contrast, the solid-state structure of [Cu(4)(POP)][PF6] features a [Cu(4)(POP)](+) cation containing a bidentate tpy-domain with the non-coordinated pyridine ring oriented with the N-atom facing away from the Cu atom; this conformation may be associated with inter-cation NHC non-classical hydrogen bonds. The photophysical properties of [Cu(N^N)(POP)][PF6] with N^N = tpy or 1–4 are described. In the solid state at room temperature, the compounds are poorly emissive. In solution, the emission behaviour is consistent with ligand dissociation. This is supported by (1)H and (31)P NMR spectroscopic data which show POP and [Cu(POP)2](+) in solutions of aged samples; mass spectrometric data are consistent with the formation of [Cu(N^N)2](2+) in these samples.

[Cu(bpy)(P^P)]⁺ containing light-emitting electrochemical cells: improving performance through simple substitution

Light-emitting electrochemical cells (LECs) containing [Cu(POP)(N^N)][PF6] (POP = bis(2-diphenylphosphinophenyl)ether, N^N = 6-methyl- or 6,6'-dimethyl-2,2'-bipyridine) exhibit luminance and efficiency surpassing previous copper(I)-containing LECs.

Coumarin meets fluorescein: a Förster resonance energy transfer enhanced optical ammonia gas sensor

This study focuses on the development of an optical ammonia gas sensor, the sensing mechanism of which is based on Förster resonance energy transfer (FRET) between coumarin and fluorescein. The dyes were immobilized into an organically modified silicate matrix during polymerizing methyltriethoxysilane with trifluoropropyltrimethoxysilane on a poly(methyl methacrylate) substrate. The resulting dye-doped xerogel films were exposed to different gaseous ammonia concentrations. A logarithmic decrease of the coumarin fluorescence emission band at 442 nm was observed with increasing gaseous ammonia concentrations, which was due to enhanced FRET between coumarin and fluorescein. The coumarin/fluorescein composition was optimized in order to obtain the best ammonia sensitivity. First experiments in a flow cell gas sensor setup demonstrated a sensitive and reversible response to gaseous ammonia.

Exceptionally long-lived light-emitting electrochemical cells: multiple intra-cation π-stacking interactions in [Ir(C^N)2(N^N)][PF6] emitters

A series of cyclometalated iridium(iii) complexes [Ir(C^N)2(N^N)][PF6] (N^N = 2,2'-bipyridine (1), 6-phenyl-2,2'-bipyridine (2), 4,4'-di-tert-butyl-2,2'-bipyridine (3), 4,4'-di-tert-butyl-6-phenyl-2,2'-bipyridine (4); HC^N = 2-(3-phenyl)phenylpyridine (HPhppy) or 2-(3,5-diphenyl)phenylpyridine (HPh2ppy)) are reported. They have been synthesized using solvento precursors so as to avoid the use of chlorido-dimer intermediates, chloride ion contaminant being detrimental to the performance of [Ir(C^N)2(N^N)][PF6] emitters in light-electrochemical cell (LEC) devices. Single crystal structure determinations and variable temperature solution 1H NMR spectroscopic data confirm that the pendant phenyl domains engage in multiple face-to-face π-interactions within the coordination sphere of the iridium(iii) centre. The series of [Ir(Phppy)2(N^N)]+ and [Ir(Ph2ppy)2(N^N)]+ complexes investigated include those with and without intra-cation face-to-face π-stacking. All the complexes display excellent luminescent properties, in particular when employed in thin solid films. The most important observation is that all the LECs using the [Ir(Phppy)2(N^N)]+ and [Ir(Ph2ppy)2(N^N)]+ emitters (i.e. with and without intra-cation π-stacking interactions) exhibit very stable luminance outputs over time, even when driven at elevated current densities. The most stable LEC had an extrapolated lifetime of more than 2500 hours under accelerated testing conditions.

4,2':6',4''-Terpyridines: diverging and diverse building blocks in coordination polymers and metallomacrocycles

4,2':6',4''-Terpyridine (4,2':6',4''-tpy) is one of the less well documented isomers of the well-established bis-chelating 2,2':6',2''-terpyridine. The N-donors of the outer rings in 4,2':6',4''-tpy subtend an angle of 120°, leading to a description of 4,2':6',4''-tpy as a divergent ligand. Because it typically binds metal ions through the outer N-donors only, 4,2':6',4''-tpy is an ideal linker for combination with metal nodes (often geometrically flexible d(10) ions) in coordination polymers and metallomacrocyclic complexes. The facile functionalization of terpyridines in the 4'-position allows access to a suite of 4'-X-4,2':6',4''-tpy ligands in which the 4'-substituent, X, can be selected to assist in directing the metal-ligand assembly process. This overview of recent advances in the chemistry of 4,2':6',4''-tpy and its 4'-substituted derivatives looks at relationships within a series of chiral polymers, competition between the formation of metallocyclic complexes versus polymers, and the use of extended aryl systems to encourage the formation of coordination polymers in which π-stacking of arene domains dominates in the assembly process. Use of metal(ii) acetates is key to the formation of paddle-wheel and larger cluster nodes that direct the assembly of both predetermined and unexpected architectures.

Divergent 4,2′:6′,4′′- and 3,2′:6′,3′′-terpyridines as linkers in 2- and 3-dimensional architectures

This Highlight illustrates the strategies applied to encourage the formation of 2- and 3-dimensional metal–organic architectures as opposed to 1-dimensional chains using 4,2′:6′,4′′- and 3,2′:6′,3′′-terpyridines as organic linkers.

Colour tuning by the ring roundabout: [Ir(C^N)2(N^N)]+ emitters with sulfonyl-substituted cyclometallating ligands

A series of fluorine-free blue and green emitting iridium complexes containing sulfone-substituted cyclometallating and pyrazolyl-pyridine ancillary ligands has been synthesized and their properties investigated.

Incorporation of a FRET dye pair into mesoporous materials: a comparison of fluorescence spectra, FRET activity and dye accessibility

The incorporation of fluorescent dyes into mesoporous silicates was investigated as potential FRET based systems for gas sensing applications with better response than non-particulate systems.

A 3-dimensional {42·84} lvt net built from a ditopic bis(3,2′:6′,3″-terpyridine) tecton bearing long alkyl tails

Divergent bis(4,2′:6′,4″-terpyridine) and bis(3,2′:6′,3″-terpyridine) tectons act as 4-connecting nodes and we demonstrate the assembly of a 3D {4²·8⁴} lvt net from the reaction of 1,4-bis(n-octoxy)-2,5-bis(3,2′:6′,3″-terpyridin-4′-yl)benzene and Co(NCS)₂.

Sticking and patching: tuning and anchoring cyclometallated ruthenium(ii) complexes

In a series of [Ru(bpy)₂(C^N)][PF₆] complexes with a variety of functionalities in the cyclometallating ligand, the absorption response is enhanced considerably by the introduction of a 4-C₆H₄P(O)(OEt)₂ anchoring domain in the C^N pyridine ring.

Programmed assembly of 4,2′:6′,4′′-terpyridine derivatives into porous, on-surface networks

4,2′:6′,4′′-Terpyridine building blocks self-assemble into hydrogen-bonded domains; addition of copper atoms results in an on-surface transformation into a coordination network.

Copper(i)-based dye-sensitized solar cells with sterically demanding anchoring ligands: bigger is not always better

DSC performances of [Cu(N⁁N_anchor)(N⁁N_ancillary)]⁺ dyes with Ph or Me groups adjacent to the copper-binding site in N⁁N_anchor are compared; electrodes with dyes that bleach are regenerated by reimmersion in dye baths containing N⁁N_anchor.

Dye-sensitized solar cells with hole-stabilizing surfaces: “inorganic” versus “organic” strategies

A study of organic and zinc(ii)-containing DSC sensitizers with second-generation diphenylamino-dendrons and benzothiadiazole domains shows that the organic dye has a superior performance.