The conventional method for creating targeted contrast agents is to conjugate separate targeting and fluorophore domains. In this study we report a new strategy based on incorporation of targeting moieties into the non-resonant structure of pentamethine and heptamethine indocyanines. Using the known affinity of phosphonates for bone minerals as a model system, we have synthesized two families of bifunctional molecules that target bone without the need for a traditional bisphosphonate. With peak fluorescence emission at ≈ 700 nm or ≈ 800 nm, these molecules can be used for FLARE dual-channel imaging. Longitudinal FLARE studies in mice demonstrate that phosphonated near-infrared fluorophores remain stable in bone for over 5 weeks, and histological analysis demonstrates incorporation into bone matrix. Taken together, we describe a new strategy for creating ultracompact, targeted, near-infrared fluorophores for various bioimaging applications.

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Inducement of high charge carrier density in organic field-effect transistors (OFETs) is a subject of immense interest due to its fundamental and applied impact on device operation. Here, the high performance of imidazolium-based ionic liquid (IL)gated OFETs is reported. By exploiting the p-doping of poly(3hexylthiophene-2,5diyl) (P3HT) in the ambient environment and using the IL-gating, high charge carrier density (10 16 cm −2 ) has been induced in P3HT, which has resulted in high hole mobility (20.2 cm 2 V −1 s −1 ). This is a remarkable improvement in fieldeffect mobility in organic polymer semiconductors. Along with high mobility, low threshold voltage (∼0.6 V), low subthreshold swing (∼100 mV dec −1 ), and specifically the high transconductance (>1 mS) position this class of devices as a strong candidate for electrical sensor platforms. The compatibility of ILs with biomolecules and the direct access to IL/P3HT interface make these devices suitable for in situ biosensors. The IL components (cation and anion) were varied (one at a time) to investigate the effect on the electrical performance of the OFETs. An increase in the gate-electrode metal work function leads to a systematic decrease in the threshold voltage (by up to 0.6 V). The mobility exhibits a negative power dependence on specific capacitance, a signature of polaronic selflocalization in organic semiconductors. The shelf life of the IL-gated OFETs is found to be more than 40 days.

The synthesis, crystal structure and luminescence properties of three cyclometalated Ir(III) complexes of general formula [(ppy)(2)Ir(pam)]X, where X = Cl(-) (1), PF(6)(-) (2), ClO(4)(-)(3), and pam = 2-picolylamine, are described. While 2 and 3 crystallize in a unique form, two pseudo-polymorphs, a solvated (1a) and a non-solvated (1b) species, have been observed for compound 1. 1a crystallizes in the monoclinic centrosymmetric space group P2(1)/c. On the contrary, 1b, 2 and 3 crystallize in the non-centrosymmetric space group P2(1)2(1)2(1) (1b) and Pca2(1) (2 and 3), respectively. All the crystalline supramolecular materials have been fully photophysically characterized. While 1 shows a bright blue-green emission in both solution and solvated crystalline state 1a, crystals of 1b, 2 and 3 show a significantly red shifted emission with respect to solution. Unexpectedly, and differently from 1a, mechanical stimuli-responsive colour and luminescence changes have been observed for 1b, 2 and 3. Upon mechanical grinding the colour of the crystalline solids changes from orange to yellow while the emission energy is partially (2 and 3) or completely (1b) converted from orange to green. The grinding-triggered colour and luminescence changes have been attributed to a crystal-to-amorphous phase conversion for all crystalline solids.