Functionalised phosphonate ester supported lanthanide (Ln = La, Nd, Dy, Er) complexes.

A series of phosphonate ester supported lanthanide complexes bearing functionalities for subsequent immobilisation on semiconductor surfaces are prepared. Six phosphonate ester ligands (L1-L6) with varying aromatic residues are synthesised. Subsequent complexation with lanthanide chloride or -nitrate precursors (Ln = La, Nd, Dy, Er) affords the corresponding mono- or dimeric lanthanide model complexes [LnX3(L1-L3 or L5-L6)3]n (X = NO3, Cl; n = 1 (Nd, Dy, Er), 2 (La, Nd)) or [LnCl2Br(L4-Br)2(L4-Cl)]n (n = 1 (Nd, Dy, Er), 2 (La, Nd)) (1-32). All compounds are thoroughly characterised, and their luminescence properties are investigated in the visible and NIR spectral regions, where applicable.

From Monodisperse Thienyl- and Furylborane Oligomers to Polymers: Modulating the Optical Properties through the Hetarene Ratio.

The application of our newly developed B-C coupling method by catalytic Si/B exchange is demonstrated for the synthesis of a series of triarylboranes (1), monodisperse thienyl- and furylborane dimers (2) and trimers (9), extended oligomers (3) and polymers (3'), as well as mixed (oligo)thienyl-/furylboranes. The structures of 1 aaTip , 1 bbTip , and 2 bbbMes* , determined by X-ray crystallography, reveal largely coplanar hetarene rings and BR3 environments, which are most pronounced in the furylborane species. Photophysical investigations, supported by TD-DFT calculations, revealed pronounced π-electron delocalization over the hetarene backbones including the boron centers. With an extended series of derivatives of varying chain lengths available, we were able to determine the effective conjugation lengths (ECL) of poly(thienylborane)s and poly(furylborane)s, which have been reached with the highest-molecular-weight derivatives of our study. Through variation of the furan-to-thiophene ratio, the photophysical properties of these materials are effectively modulated. Significantly, higher furan contents lead to considerably increased fluorescence intensities. Compounds 1 aaTip , 1 bbTip , and 3 aTip showed the ability to bind fluoride anions. The binding process is signaled by a distinct change in their optical absorption characteristics, thus rendering these materials attractive targets for sensory applications.

PBP bridged [3]ferrocenophane: a bisphosphanylborane with a redox trigger.

Stereospecific access to the unprecedented P-B-P bridged [3]ferrocenophane Fe(C5H4PtBu)2BMes is presented. In contrast to acyclic ferrocenylphosphanes, we find evidence for a shift of spin-density from Fe to P upon pyramidal inversion of the P centers in the mono-cation; the latter has a lifetime of τ = 0.31(4) s.

Catalytic B-C Coupling by Si/B Exchange: A Versatile Route to π-Conjugated Organoborane Molecules, Oligomers, and Polymers.

Conjugated organoboranes have emerged as attractive hybrid materials for optoelectronic applications. Herein, a highly efficient, environmentally benign catalytic B-C bond formation method is presented that uses organosilicon compounds, dibromoboranes, and the metal-free organocatalyst Me3SiNTf2. This Si/B exchange approach has been successfully applied to the synthesis of arylborane molecules 4a-c, oligomers 8a,b, and polymers 8a',b'. Photophysical investigations, supported by TD-DFT calculations, reveal highly effective π-conjugation in thienyl- and furylborane species; the latter are also highly emissive.

Poly(p-phenylene iminoborane): A Boron-Nitrogen Analogue of Poly(p-phenylene vinylene).

Substitution of selected CC units in π-conjugated organic frameworks by their isoelectronic and isosteric BN units (BN/CC isosterism) has proven to be a successful concept for the development of BN-doped polycyclic aromatic hydrocarbons (PAHs) with intriguing properties and functions. The first examples have just demonstrated the applicability of this approach to polymer chemistry. Herein, we present the synthesis and comprehensive characterization of the first poly(p-phenylene iminoborane). This novel inorganic-organic hybrid polymer can be regarded as a BN analogue of the well-known poly(p-phenylene vinylene) (PPV). Photophysical investigations on the polymer and a series of model oligomers provide clear evidence of some π-conjugation across the B=N bonds and extension of the conjugation path with increasing chain length. TD-DFT calculations provide deeper insight into the electronic structure of the new materials.

Dehydrocoupling and Silazane Cleavage Routes to Organic-Inorganic Hybrid Polymers with NBN Units in the Main Chain.

Despite the great potential of both π-conjugated organoboron polymers and BN-doped polycyclic aromatic hydrocarbons in organic optoelectronics, our knowledge of conjugated polymers with B-N bonds in their main chain is currently scarce. Herein, the first examples of a new class of organic-inorganic hybrid polymers are presented, which consist of alternating NBN and para-phenylene units. Polycondensation with B-N bond formation provides facile access to soluble materials under mild conditions. The photophysical data for the polymer and molecular model systems of different chain lengths reveal a low extent of π-conjugation across the NBN units, which is supported by DFT calculations. The applicability of the new polymers as macromolecular polyligands is demonstrated by a cross-linking reaction with Zr(IV) .