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Diamagnetic achiral pyrene and phenanthrene derivatives substituted with electron-donating hydroxyl/methoxy groups and electron-withdrawing carboxylic acid groups exhibited clear magnetic circularly polarised luminescence (MCPL) spectra at 360-460 nm in dilute solvents upon the application of N-up and S-up Faraday geometries under an external magnetic field of 1.6 T. Their MCPL signs were also susceptible upon application of the same Faraday geometry.

Optically inactive, paramagnetic Ir(iii)(ppy) 3 and Ir(iii)(ppy) 2 (acac) (ppy: 2-phenylpyridinate and acac: acetylacetonate) showed nearly mirror-symmetric magnetic circularly polarised luminescence (MCPL) spectra in dilute dichloromethane and dimethyl sulfoxide under N-up and S-up geometries in a 1.6-T magnetic field. However, the MCPL signs of Ir(iii)(ppy) 3 and Ir(iii)(ppy) 2 (acac) under the same N-up (or S-up) Faraday geometry were opposite to each other when one ppy was replaced with an acac. This ligand exchange approach provides facile control of the MCPL sign, irrespective of the Faraday geometry.

Although 12 diamagnetic fused aromatics with or without substituents exhibit mirror-symmetric magnetic circularly polarised luminescence (MCPL) through N-up and S-up Faraday geometries under a magnetic field intensity of 1.6 T, their signs (single and multiple) and magnitudes depend strongly on either the aromatic structures or the peripheral positions of the substituents., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Five optically inactive EuIII(hfa)3, TbIII(hfa)3, EuIII(acac)3·Phen, TbIII(acac)3·Phen and EuIII(hfa)3·BDPB (hfa: hexafluoroacetylacetonate, acac: acetylacetonate, BDPB: 2,2'-bis(diphenylphosphino)biphenyl and Phen: phenanthroline) complexes showed clear mirror-image magnetic circularly polarised luminescence (MCPL) spectra in CHCl3, acetone, and DMF solutions, in a poly(methyl methacrylate) film, a KBr pellet and bulk powder at room temperature under 1.6 T as an external magnetic field with Faraday geometry. The signs of the MCPL signals were determined via N-up and S-up geometries. The gMCPL values of EuIII(hfa)3 and TbIII(hfa)3 were ±(0.046-2.0) × 10-2 T-1 at the 5D0 → 5FJ transitions (J = 1-4) in the range of 590 nm and 703 nm and ±(0.0081-1.0) × 10-2 T-1 at the 5D4 → 7FJ transitions (J = 3-6) in the range of 480 nm and 630 nm, respectively. Interestingly, the photoluminescence spectra of EuIII(hfa)3 and TbIII(hfa)3 in CHCl3 and acetone under 1.6 T considerably redshifted by 10-114 cm-1, while those of EuIII(acac)3·Phen and TbIII(acac)3·Phen did not reveal detectable redshifts.

A Ni(0)-mediated coupling reaction of a 1,8-dibromopyrene gave a series of cyclic pyrene oligomers CPn up to nonadecamer. CP5 and CP7 represent a unique class of asymmetric compounds with no stereogenic chiral centers in terms of their global chirality, which are achieved because of an odd number of pyrenes.

The left and right helicities of azobenzene (Azo)-containing main-chain polymer (PF8Azo) were successfully controlled with an enantiomeric pair of rigid rod-like helical polysilanes carrying ( S )- and ( R )-2-methylbutyl groups (PSi- S and PSi- R , respectively) as their hetero-aggregates in a mixture of chloroform and methanol solvents and in the solid state. Optimizing the good and poor cosolvents and their volume fractions showed that the molar ratio of PF8Azo to PSi- S /- R and the molecular weight of PF8Azo were crucial to boost the CD amplitudes of PF8Azo/PSi- S and PF8Azo/PSi- R hetero-aggregates. The photoresponsive trans - cis transformation caused noticeable changes in the sign and magnitude of the chiroptical behavior due to the hetero-aggregates. Moreover, the optically active PF8Azo homo-aggregates were produced by complete photoscissoring reactions at 313 nm, which could be assigned to the Siσ-Siσ* transitions of PSi- S and PSi- R ., Competing Interests: The authors declare no competing financial interest., (This journal is © The Royal Society of Chemistry.)

A C 2 -symmeric binaphthyl framework bearing phenanthrene as the emitter exhibited circularly polarised luminescence (CPL) in dilute solutions. The CPL and circular dichroism signs of the luminophores were altered by solvents (chloroform, methanol, acetonitrile, and dimethylformamide). DFT and TD-DFT calculations indicated that the dihedral angle between the phenanthrene and naphthyl rings was responsible for the apparent sign inversion. The role of solvent molecules in the ground and photoexcited states was discussed based on Hansen solubility parameters (δ, δ d , δ p and δ h ).

Multiple pyrenes as pendants of enantioimpure di-/tripeptides (abbreviated as N-LD-C, N-DL-C, N-LLD-C and N-DDL-C) showed pyrene-origin CPL and CD signals, which were associated with conflicting CPL-/CD-signs, compared to the corresponding enantiopure di-/tri-peptides.

Complexes of Eu(iii)(hfa) 3 with a C 2 -symmetric planar P(iii) ligand exhibited intense circularly polarised luminescence (CPL) due to 5 D 0 → 7 F 1 and 5 D 0 → 7 F 2 transitions, with the signs and shapes of CPL signals depending on the choice of solvent (acetone or chloroform).

Among l- and d-oligopeptides with multiple pyrenes as pendants, the dipeptides with two and three pyrenes showed blue-coloured circularly polarised luminescence as high as |gem|≈ (0.86-1.1) × 10(-2) at around 450 nm, reflecting from exciton couplets of twisted pyrenes.

2,2-Dimethyl-1,3-dioxolane connected to two pyrene moieties through flexible wires in chloroform exhibited cryptochirality in the ground state, as proven by the lack of detectable circular dichroism signals. This cryptochirality was deciphered in the photoexcited state by circularly polarised luminescence signals.

We investigated the ground- and photoexcited-state chiralities of two chiral fluorophores with a rigid framework embedded in two achiral polyurethanes as the solid matrices. As the fluorophores, we used two pairs of atropisomeric binaphthyl derivatives, (R)-(−)-1,1′-binaphthyl-2,2′-diyl hydrogen phosphate [(R)-1a] and (R)-(−)-(3,5-dioxa-4-phosphacyclohepta-[2,1-a:3,4-a′]dinaphthalen-4-yl)-dimethylamine [(R)-1b], and for comparison, their optical antipodes (S)-1a and (S)-1b. As the solid matrices, we used two soluble achiral polyurethanes (2a and 2b) derived from the naturally occurring myo-inositol as the building block, because these polymers had a high glass transition temperature of ~150 °C. The chiral fluorophores in the polyurethanes emitted circularly polarised luminescence with a high circular anisotropy of ~0.6–1.5 × 10(-3). Regardless of the matrix, (R)- and (S)-1a had nearly mirror-image chiroptical properties in the ground and photoexcited states, as did (R)- and (S)-1b.

The fluorescent modes and signs of the circularly polarized luminescence of an axially chiral binaphthyl-pyrene organic fluorophore were successfully controlled by changing from a fluidic chloroform solution to a glassy poly(methyl methacrylate) solid film.

Tethering four 1- versus 2-naphthyls to the same chiral scaffold derived from tartaric acid led to oppositely signed circularly polarized luminescence (CPL) and circular dichroism (CD) in solution, which not only reveals the decisive role of the spatial arrangement of chromophores/fluorophores in determining the chiroptical behaviors but also provides us with a versatile tool for switching the signs of CPL and CD without using the antipodal scaffold.

Circularly polarised luminescence (CPL) and photoluminescence (PL) properties of π-conjugated (R)- and (S)-2,2'-diphenyl-4-biphenanthrol (VAPOL) exhibited an efficient CPL (∼1.3 × 10(-3)) with a quantum yield (ΦF) of 0.20 at 376 nm. By comparison, (R)- and (S)-3,3-diphenyl-2,2-bi-1-naphthol (VANOL) exhibited no CPL or PL.

The side chain chirality of a poly(diphenylacetylene) derivative was transferred and amplified spontaneously from solution to a bulk film due to lyotropic liquid crystallinity.

We observed the emergence and inversion of chiroptical handedness in three chiroptically silent dialkylpolysilanes during aggregation in limonene-methanol-THF tersolvents.

An optically active, π-stacked poly[2,7-bis(4-tert-butylphenyl)dibenzofulvene] having a preferred-handed helical conformation was synthesized by anionic polymerization. A thin film sample of the polymer exhibited broad-band white circularly polarized light (CPL) emission on photo excitation.

Various half-sandwich titanium complexes containing iminoimidazolidide ligands, CpTiCl(2)[1,3-R(2)(CH(2)N)(2)C=N] (1a-d) [R = Ph (a), 2,6-Me(2)C(6)H(3) (b), cyclohexyl (c), (t)Bu (d)], have been employed as the catalyst precursors for ethylene polymerisation, syndiospecific styrene polymerisation, and copolymerisation of ethylene with 1-hexene in the presence of MAO cocatalyst; 1d showed the highest catalytic activity for ethylene polymerisation whereas 1b showed the highest activity for syndiospecific styrene polymerisation., (This journal is © The Royal Society of Chemistry 2011)

Liquid crystalline diphenylacetylene polymer derivatives showed piezochromic fluorescence via order-to-disorder phase transition.

The significant variation in photoluminescence emission of poly(diphenylacetylene) derivatives according to the substitution position is due to the differences in the intramolecular pi-stack structure and chain conformation.

Tris(pyrazolyl)borate titanium(IV) complexes containing aryloxo ligand of type, TpTiCl(2)(OAr) [Tp = HB(pyrazolyl)(3); Ar = 2-(i)PrC(6)H(4), C(6)F(5), 2,6-Ph(2)C(6)H(3)], have been prepared, identified, and the structures of TpTiCl(2)(OC(6)F(5)), TpTiCl(2)(O-2,6-Ph(2)C(6)H(3)) have been determined by X-ray crystallography. The 2-(i)PrC(6)H(4) analogue exhibits especially high catalytic activities for ethylene polymerisation in the presence of methylaluminoxane (MAO), and the activity by TpTiCl(2)(OAr) increased in the order: Ar = 2-(i)PrC(6)H(4) > Ph > C(6)F(5) >> 2,6-Ph(2)C(6)H(3) > 2,6-Me(2)C(6)H(3), 2,6-(i)Pr(2)C(6)H(3).

A spontaneous resolution chiral fluorescent system is prepared by using 2-anthracenecarboxylic acid, and racemic (rac)-1-phenylethylamine or rac-1-cyclohexylethylamine. Although chiral functional organic materials are usually prepared using chiral molecules, in this system, a chiral organic fluorophore, which exhibits fluorescence in the solid state, is prepared from achiral and rac molecules.

For chain-like polymers on surfaces, the relationship between chain topology and inherent physical properties has long been puzzling due to the lack of proper models and detection systems with ultrahigh sensitivity and high accuracy. Among various chain-like polymers, soluble organopolysilane is one suitable model for elucidating the uniqueness of chain-like polymers on surfaces because of its (1) controllable molecular length, polydispersity, stiffness, and terminal group by an adequate molecular design, a careful synthesis, and a precise purification, and (2) highly luminescent chromophore due to Siσ-Siσ* transition of the Si main chain. This review comprehensively covers the works on (i) molecular imaging with scanning probe microscopy, (ii) tethering on surfaces by a grafting-to approach, (iii) self-assembly, (iv) structural phase transition, (v) orientational phase transition, and (vi) chiroptical switching, memory and amplification in single and double layer films deposited on solid surfaces. This knowledge and understanding may stimulate advanced studies on polymer-based nanoscience, nanotechnology, and nanofabrication as well as in traditional surface chemistry and polymer physics.

Unique conformations such as rod, semicircle, and circle structures of isolated semi-flexible helical polysilanes were observed by atomic force microscopy (AFM); the chain topology was significantly related to the chain length (molecular weight) on the surfaces.

CpTiCl2(N=CtBu2) exhibits both remarkable catalytic activity and efficient norbornene (NBE) incorporation for ethylene-NBE copolymerization: the NBE incorporation by Cp'TiCl2(X) (X = N=CtBu2, O-2,6-iPr2C6H3; Cp' = Cp, C5Me5, indenyl) was related to the calculated coordination energy after ethylene insertion.

Cooperative amplification of the C-F...Si weak interaction between side chains and the main chain was found to afford rigid rodlike helical polysilanes with a preferential screw sense.

The first unsymmetrically substituted polyfluorene bearing a bulky poly(benzyl ether) dendron and less bulky 3,6-dioxaoctyl groups in the 9-position was designed and synthesized, which gives almost a pure bluish photoluminescence with negligible weak greenish excimer emission around 520 nm even in a thermally annealed thin solid film.