SYNTHESIS AND CHARACTERIZATIONS OF NEAR INFRARED ABSORBING POLYMERS

A series of near infrared (NIR) absorbing dinuclear ruthenium dicarbonylhydrazine complexes (DCH-Ru),[{Ru(bpy)_2)_2μ-DCH]~(n ) (where bpy = 2,2'-bipyridinc and n = 2, 3 or 4), were prepared. The DCH-Ru complexes areelectrochromic in the NIR region with a high absorption coefficient at 1550-1600 nm typically over 10000 M~(-1)cm~(-1). DCH-Ru complex polymers with good NIR electrochromic properties were also obtained and processed to make a device foroptical attenuation at a wavelength of 1550 nm. The potential of these DCH-Ru polymers for use in a variable opticalattenuator has been demonstrated with an attenuating power at the 1550-nm telecommunication wavelength over 7.0 dB permicron of polymer film thickness. Other classes of NIR active materials are the pentacenediquinones and the correspondingpoly(ether pentacenediquinone)s. These polymers can be electrochemically reduced to the corresponding semiquinone(radical anion) having NIR absorption within a telecom window (e. g., 1310 nm).     

Low band‐gap diketopyrrolopyrrole‐containing polymers for near infrared electrochromic and photovoltaic applications

Donor–acceptor type polymers bearing diketopyrrolopyrrole and 3,4‐ethylenedioxythiophene units are reported. The polymers are green and exhibit very low band‐gaps (1.19 eV) with strong and broad absorption (maxima of about 830 nm) in the near infrared (NIR) region in their neutral film states. The polymers display color changes between dark green and light blue with exceptional optical contrasts in the NIR regions of up to 78 and 63% as thin films and single‐layer electrochromic devices, respectively. Fast switching, good stabilities as well as high coloration efficiencies (743–901 cm² C^?1) were also observed. The polymers could also be potentially used as photovoltaic material, with a power conversion efficiency of up to 1.68%. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 1287–1295     

Preparation and characterization of conjugated polymers made by postpolymerization reactions of alternating polyketones

Conjugated polymers possessing a poly(2,5-dimethylene-2,5-dihydrofuran) backbone were prepared through postpolymerization reaction of styrenic polyketones with bromine in one-pot reactions. The modification is proposed to proceed via condensation of two repeating units to form a fully characterized polymer with a poly(2,5-dimethylenetetrahydrofuran) backbone. Subsequent bromination and elimination of HBr yield a polymer with a fully conjugated carbon backbone. The new conjugated polymers were characterized by NMR, IR, and UV-vis spectroscopies and by CV. These polymers have strong absorption in the visible region, with the absorption peaks shifted to the NIR region upon doping with acids. The ease of the synthesis of the starting polyketone and of the modifications allows large-scale preparation of those conjugated polymers.     

Side Chain Functional Conjugated Porous Polymers for NIR Controlled Carbon Dioxide Adsorption and Release

Conjugated porous polymers exhibit considerable advantage as attractive candidate for carbon dioxide(CO₂) capture. However, the regeneration of the CO₂ still faces the problem of high energy cost. Here we synthesize a near-infrared region(NIR) light responsive conjugated porous polymer(PDPP-Gu) {DPP=3,6-di(thiophen-2-yl)pyrrolo[3,4-c]pyrrole-1,4(2H,5H)-dione} by constructing porous amorphous networks with a side chain engineering strategy to regulate CO₂ adsorption and release through photothermal conversion. The PDPP-Gu is featured by a torsional conjugated backbone as well as a functional side chain of guanidino group. The donor-acceptor configuration of PDPP-Gu afforded strong absorption in the NIR and an excellent photothermal conversion capability of up to 48.8%, as well as a high surface energy. Moreover, guanidine modified side chain further enhanced the CO₂-polymers interactions, resulting in a high CO₂ selective adsorption capacity(0.8 mmol/g) at 273 K, 1 bar(1 bar=10⁵ Pa). The adsorbed CO₂ can be released under NIR light irradiation. This strategy of molecule design combined the dual features of photothermal conversion and gas adsorption, which is beneficial for the development of materials to dynamically control the adsorption and release of CO₂ through NIR light.     

Photoinduced electron transfer and nonlinear absorption in poly(carbazole-alt-2,7-fluorene)s bearing perylene diimides as pendant acceptors

This paper reports the synthesis, photophysical behavior, and use in nanosecond optical-pulse suppression of a poly(2,7-carbazole-alt-2,7-fluorene) and a poly(3,6-carbazole-alt-2,7-fluorene) in which the carbazole N-positions are linked by an alkyl chain to one of the nitrogen atoms of a perylene-3,4,9,10-tetracarboxylic diimide (PDI) acceptor. It was found that the PDI pendants on the polymer side chain aggregated even in dilute solution, which extended the onset of PDI absorption into the near-infrared (NIR). Transient-absorption spectra of these polymers provide evidence for efficient electron transfer following either donor or acceptor photoexcitation to form long-lived charge-separated species, which exhibit strong absorption in the NIR. The spectral overlap between the transient species and the long-wavelength absorption edge of the aggregated PDI leads to reverse saturable absorption at 680 nm that can be used for optical-pulse suppression. Additionally, at high input energies, two-photon absorption mechanisms may also contribute to the suppression. PDI-grafted polymers exhibit enhanced optical-pulse suppression compared with blends of model materials composed of unfunctionalized poly(carbazole-alt-2,7-fluorene)s and PDI small molecules.     

Low‐Band Gap Polymeric Cyanine Dyes Absorbing in the NIR Region

Two new, fully conjugated polymeric cyanine dyes based on trimethine and heptamethine moieties have been synthesized. Both polymers were characterized by gel permeation chromatography, UV‐vis and IR spectroscopy, elementary analysis and cyclic voltammetry. The structure of one material could be confirmed with NMR spectroscopy. Upon head‐to‐tail coupling of the dye moieties distinct bathochromic shifts up to 159 nm were observed for the polymers which absorb solely in the near infrared (NIR) region with maxima up to 1 002 nm and very high molar absorption coefficients. This highly efficient absorption in the NIR spectral domain combined with the strong electron accepting properties makes these dyes interesting candidates for many optical applications; investigations on photovoltaic devices based on polymeric cyanine dye/C₆₀ heterojunctions identify one of these possibilities.

     

Spectroscopic studies of Pyrococcus furiosus superoxide reductase: implications for active-site structures and the catalytic mechanism

The combination of UV/visible/NIR absorption, CD and variable-temperature magnetic circular dichroism (VTMCD), EPR, and X-ray absorption (XAS) spectroscopies has been used to investigate the electronic and structural properties of the oxidized and reduced forms of Pyrococcus furiosus superoxide reductase (SOR) as a function of pH and exogenous ligand binding. XAS shows that the mononuclear ferric center in the oxidized enzyme is very susceptible to photoreduction in the X-ray beam. This observation facilitates interpretation of ground- and excited-state electronic properties and the EXAFS results for the oxidized enzyme in terms of the published X-ray crystallographic data (Yeh, A. P.; Hu, Y.; Jenney, F. E.; Adams, M. W. W.; Rees, D. C. Biochemistry 2000, 39, 2499-2508). In the oxidized state, the mononuclear ferric active site has octahedral coordination with four equatorial histidyl ligands and axial cysteinate and monodentate glutamate ligands. Fe EXAFS are best fit by one Fe-S at 2.36 A and five Fe-N/O at an average distance of 2.12 A. The EPR-determined spin Hamiltonian parameters for the high-spin (S = (5)/(2)) ferric site in the resting enzyme, D = -0.50 +/- 0.05 cm(-1) and E/D = 0.06, are consistent with tetragonally compressed octahedral coordination geometry. UV/visible absorption and VTMCD studies facilitate resolution and assignment of pi His --> Fe(3+)(t(2g)) and (Cys)S(p) --> Fe(3+)(t(2g)) charge-transfer transitions, and the polarizations deduced from MCD saturation magnetization studies indicate that the zero-field splitting (compression) axis corresponds to one of the axes with trans-histidyl ligands. EPR and VTMCD studies provide evidence of azide, ferrocyanide, hydroxide, and cyanide binding via displacement of the glutamate ligand. For azide, ferrocyanide, and hydroxide, ligand binding occurs with retention of the high-spin (S = 5/2) ground state (E/D = 0.27 and D < 0 for azide and ferrocyanide; E/D = 0.25 and D = +1.1 +/- 0.2 cm(-1) for hydroxide), whereas cyanide binding results in a low-spin (S = 1/2) species (g = 2.29, 2.25, 1.94). The ground-state and charge-transfer/ligand-field excited-state properties of the low-spin cyanide-bound derivative are shown to be consistent with a tetragonally elongated octahedral coordination with the elongation axis corresponding to an axis with trans-histidyl ligands. In the reduced state, the ferrous site of SOR is shown to have square-pyramidal coordination geometry in frozen solution with four equatorial histidines and one axial cysteine on the basis of XAS and UV and NIR VTMCD studies. Fe EXAFS are best fit by one Fe-S at 2.37 A and four Fe-N/O at an average distance of 2.15 A. VTMCD reveals a high-spin (S = 2) ferrous site with (Cys)S(p) --> Fe(2+) charge-transfer transitions in the UV region and (5)T(2g) --> (5)E(g) ligand-field transitions in the NIR region at 12400 and <5000 cm(-1). The ligand-field bands indicate square-pyramidal coordination geometry with 10Dq < 8700 cm(-1) and a large excited-state splitting, Delta (5)E(g) > 7400 cm(-1). Analysis of MCD saturation magnetization data leads to ground-state zero-field splitting parameters for the S = 2 ground state, D approximately +10 cm(-1) and E/D approximately 0.1, and complete assessment of ferrous d-orbital splitting. Azide binds weakly at the vacant coordination site of reduced SOR to give a coordination geometry intermediate between octahedral and square pyramidal with 10Dq = 9700 cm(-1) and Delta (5)E(g) = 4800 cm(-1). Cyanide binding results in an octahedral ferrous site with 10Dq = 10,900 cm(-1) and Delta (5)E(g) = 1750 cm(-1). The ability to bind exogenous ligands to both the ferrous and ferric sites of SOR is consistent with an inner-sphere catalytic mechanism involving superoxide binding at the ferrous site to yield a ferric-(hydro)peroxo intermediate. The structural and electronic properties of the SOR active site are discussed in relation to the role and bonding of the axial cysteine residue and the recent proposals for the catalytic mechanism.     

ATOP dyes. optimization of a multifunctional merocyanine chromophore for high refractive index modulation in photorefractive materials.

This paper reports synthesis, characterization and structural optimization of amino-thienyl-dioxocyano-pyridine (ATOP) chromophores toward a multifunctional amorphous material with unprecedented photorefractive performance. The structural (dynamic NMR, XRD) and electronic (UV/vis, electrooptical absorption, Kerr effect measurements) characterization of the ATOP chromophore revealed a cyanine-type pi-conjugated system with an intense and narrow absorption band (epsilon(max) = 140 000 L mol(-)(1) cm(-)(1)), high polarizability anisotropy (deltaalpha(0) = 55 x 10(-)(40) C V(-)(1) m(2)), and a large dipole moment (13 D). This combination of molecular electronic properties is a prerequisite for strong electrooptical response in photorefractive materials with low glass-transition temperature (T(g)). Other important materials-related properties such as compatibility with the photoconducting poly(N-vinylcarbazole) (PVK) host matrix, low melting point, low T(g), and film-forming capabilities were optimized by variation of four different alkyl substituents attached to the ATOP core. A morphologically stable PVK-based composite containing 40 wt % of ATOP-3 showed an excellent photorefractive response characterized by a refractive index modulation of Deltan approximately 0.007 and a gain coefficient of Gamma approximately 180 cm(-)(1) at a moderate electrical field strength of E = 35 V microm(-)(1). Even larger effects were observed with thin amorphous films consisting of the pure glass-forming dye ATOP-4 (T(g) = 16 degrees C) and 1 wt % of the photosensitizer 2,4,7-trinitro-9-fluorenylidene-malononitrile (TNFM). This material showed complete internal diffraction at a field strength of only E = 10 V microm(-)(1) and Deltan reached 0.01 at only E = 22 V microm(-)(1) without addition of any specific photoconductor.     

Synthesis, characterization and photovoltaic properties of platinum-containing poly(aryleneethynylene) polymers with phenanthrenyl-imidazole moiety

A new type of soluble, solution-processable platinum(II) polyyne polymers based on phenanthrenyl-imidazole chromophore and their corresponding diplatinum model complexes were synthesized via the CuI-catalyzed dehydrohalogenation reaction of the platinum(II) chloride precursor and each of the diethynyl ligands. The photophysical (absorption and emission spectra), thermal, electrochemical and photovoltaic properties of the polymers were investigated. Both polymers exhibit strong absorption bands centered at 459-466 nm. The effect of adding thiophene ring along the polymer backbone was evaluated. Bulk heterojunction solar cells fabricated by blending these metallopolymers with methanofullerene were studied, with the power conversion efficiency reaching 0.39%, although the band gap energies of the polymers are not low.     

Electronic Characterization of Vis–NIR Absorbing Noninnocent Ruthenium Oxyquinolate–merocyanine Complexes and their Photoacoustic Emission in Aqueous Micellar Solution†

The electronic and photophysical properties for a series of ruthenium(II) polypyridyl dyes are presented where a π-accepting 5-(vinyl-cyanine)-8-oxyquinolate class of ligand is incorporated to yield an improved vis–NIR absorption. A combination of computational, UV–vis–NIR absorption, phosphorescence emission and cyclic voltammetry studies are used to probe the influence of these ligands on complex electronic and photophysical properties. To assess their potential as vis–NIR photoacoustic contrast agents, select complexes were formulated in a PBS buffer/Tween® 20 solvent system. The p-quinolin-1-ium, 1,3,3-trimethyl-3H-indol-1-ium and 1,1,3-trimethyl-1H-benzo[e]indol-3-ium acceptor groups each impart a strong 680 nm optical absorption and photoacoustic emission on par with the performance exhibited by both the methylene blue and cryptocyanine commercial dyes.     

Modular Establishment of a Diketopyrrolopyrrole‐Based Polymer Library via Pd‐Catalyzed Direct C–H (Hetero)arylation: a Highly Efficient Approach to Discover Low‐Bandgap Polymers

A concise, highly efficient palladium‐catalyzed direct C–H (hetero)arylation is developed to modularly assemble a diketopyrrolopyrrole ( DTDPP )‐based polymer library to screen low‐bandgap and near‐infrared (NIR) absorbing materials. The DTDPP ‐based copolymers P1 and P2 with an alternating donor–acceptor–donor–acceptor (D–A–D–A) sequence and the homopolymer P9 exhibit planarity and excellent π‐conjugation, which lead to low bandgaps (down to 1.22 eV) as well as strong and broad NIR absorption bands (up to 1000 nm).     

Water-soluble NIR fluorescent probes based on squaraine and their application for protein labeling.

Water-soluble near-infrared (NIR) fluorescent labeling probes, named KSQ-3 and -4, which are based on a squaraine backbone, were synthesized and applied to biological labeling. The presented results demonstrate that the large, planar and hydrophobic squaraine dye becomes fully soluble in aqueous solution by the introduction of several sulfo group terminated alkyl substituents. Especially KSQ-4, which is substituted with four sulfo groups, exhibited perfect water solubility and significant fluorescence emission at the NIR region (817 nm) in the presence of bovine serum albumin (BSA). BSA was covalently labeled with KSQ-4, and the conjugate showed a strong absorption peak at 787 nm, which indicates compatibility with commercially available NIR laser diodes used for exciting the fluorophore. Furthermore, strong fluorescence emission was observed at 812 nm (phi = 0.08).     

Potentiometric, electronic structural, and ground- and excited-state optical properties of conjugated bis[(porphinato)zinc(II)] compounds featuring proquinoidal spacer units

We report the synthesis, optical, electrochemical, electronic structural, and transient optical properties of conjugated (porphinato)zinc(II)-spacer-(porphinato)zinc(II) (PZn-Sp-PZn) complexes that possess intervening conjugated Sp structures having varying degrees of proquinoidal character. These supermolecular PZn-Sp-PZn compounds feature Sp moieties {(4,7-diethynylbenzo[c][1,2,5]thiadiazole (E-BTD-E), 6,13-diethynylpentacene (E-PC-E), 4,9-diethynyl-6,7-dimethyl[1,2,5]thiadiazolo[3,4-g]quinoxaline (E-TDQ-E), and 4,8-diethynylbenzo[1,2-c:4,5-c']bis([1,2,5]thiadiazole) (E-BBTD-E)} that regulate frontier orbital energy levels and progressively increase the extent of the quinoidal resonance contribution to the ground and electronically excited states, augmenting the magnitude of electronic communication between terminal (5,-10,20-di(aryl)porphinato)zinc(II) units, relative to that evinced for a bis[(5,5',-10,20-di(aryl)porphinato)zinc(II)]butadiyne benchmark (PZnE-EPZn). Electronic absorption spectra show significant red-shifts of the respective PZn-Sp-PZn x-polarized Q state (S0 --> S1) transition manifold maxima (240-4810 cm(-1)) relative to that observed for PZnE-EPZn. Likewise, the potentiometrically determined PZn-Sp-PZn HOMO-LUMO gaps (E1/2(0/+) - E1/2(-/0)) display correspondingly diminished energy separations that range from 1.88 to 1.11 eV relative to that determined for PZnE-EPZn (2.01 eV). Electronic structure calculations provide insight into the origin of the observed PZn-Sp-PZn electronic and optical properties. Pump-probe transient spectral data for these PZn-Sp-PZn supermolecules demonstrate that the S1 --> S(n) transition manifolds of these species span an unusually broad spectral domain of the NIR. Notably, the absorption maxima of these S1 --> S(n) manifolds can be tuned over a 1000-1600 nm spectral region, giving rise to intense excited-state transitions approximately 4000 cm(-1) lower in energy than that observed for the analogous excited-state absorption maximum of the PZnE-EPZn benchmark; these data highlight the unusually large quinoidal resonance contribution to the low-lying electronically excited singlet states of these PZn-Sp-PZn species. The fact that the length scales of the PZn-Sp-PZn species (approximately 25 angstrom) are small with respect to those of classic conducting polymers, yet possess NIR S1 --> S(n) manifold absorptions lower in energy, underscore the unusual electrooptic properties of these conjugated structures.     

Highly near‐infrared photoluminescence from aza‐borondipyrromethene‐based conjugated polymers

Near‐infrared (NIR) emissive conjugated polymers were prepared by palladium‐catalyzed Sonogashira polymerization of diiodobenzene‐functionalized aza‐borondipyrromethene (Aza‐BODIPY) monomers, which were substituted at 3 and 5 or 1 and 7 positions on the Aza‐BODIPY core, with 1,4‐diethynyl‐2,5‐dihexadecyloxybenzene or 3,3′‐didodecyl‐2,2′‐diethynyl‐5,5′‐bithiophene. The structures of the polymers were confirmed by ¹H NMR, ¹³C NMR, ¹¹B NMR, Fourier transform infrared (FT‐IR) spectroscopies, and size exclusion chromatography (SEC). The optical properties were then characterized by UV–vis absorption and photoluminescence (PL) spectroscopies, and theoretical calculation using density‐functional theory (DFT) method. The polymers were fusible and soluble in common organic solvents including tetrahydrofuran (THF), o‐xylene, toluene, CHCl₃, and CH₂Cl₂, etc. The UV–vis absorption and PL spectra of the polymers shifted to long wavelength region in comparison with simple Aza‐BODIPY as the counterpart because of extended π‐conjugation of the polymers. The polymers efficiently emitted NIR light with narrow emission bands at 713～777 nm on excitation at each absorption maximum. Especially, the polymer attached 1,4‐diethynyl‐2,5‐dihexadecyloxybenzene to 3,5‐position on the core revealed intense quantum yields (?_F = 24%) in this NIR region (753 nm). © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Novel Ru-dioxolene complexes as potential electrochromic materials and NIR dyes

A series of Ru(bpy)(2)-dioxolene complexes 1-4 (bpy = 2,2'- bipyridine) and corresponding Ru(dcb)(2)-dioxolene complexes 5-8 (dcbH(2) = 2,2'-bipyridine-4,4'-dicarboxylic acid) have been prepared, and their spectroelectrochemical behavior in solution has been investigated. The complexes show reversible electrochemical behavior accompanied by a strong NIR absorption in their semiquinone forms due to a Ru(dpi) --> sq(pi) MLCT band. Complete quenching of the NIR absorption occurs both upon oxidation (to the quinone form) and upon reduction (to the catechol form) very close to 0 V. The color of the systems can be tuned by using a wide range of ligands. The complexes 5-8 can be anchored onto nanocrystalline inorganic semiconductors allowing incorporation into potential electrochromic devices. As a proof of principle, compound 8 has been adsorbed on nanocrystalline Sb-doped SnO(2) supported on FTO glass, and it displays reversibly switchable electrochromic behavior in the NIR.     

Controlling Energy Gaps of π-Conjugated Polymers by Multi-Fluorinated Boron-Fused Azobenzene Acceptors for Highly Efficient Near-Infrared Emission

We demonstrate that multi-fluorinated boron-fused azobenzene (BAz) complexes can work as a strong electron acceptor in electron donor-acceptor (D-A) type π-conjugated polymers. Position-dependent substitution effects were revealed, and the energy level of the lowest unoccupied molecular orbital (LUMO) was critically decreased by fluorination. As a result, the obtained polymers showed near-infrared (NIR) emission (λ_PL=758–847 nm) with high absolute photoluminescence quantum yield (Φ_PL=7–23%) originating from low-lying LUMO energy levels of the BAz moieties (−3.94 to −4.25 eV). Owing to inherent solid-state emissive properties of the BAz units, deeper NIR emission (λ_PL=852980 nm) was detected in film state. Clear solvent effects prove that the NIR emission is from a charge transfer state originating from a strong D-A interaction. The effects of fluorination on the frontier orbitals are well understandable and predictable by theoretical calculation with density functional theory. This study demonstrates the effectiveness of fluorination to the BAz units for producing a strong electron-accepting unit through fine-tuning of energy gaps, which can be the promising strategy for designing NIR absorptive and emissive materials.     

Design, synthesis, and characterization of a calcium-sensitive near infrared dye

Intracellular calcium concentration in biological cells varies from 0.1 to 10 μM depending upon cell signaling and disease states. A direct estimate of calcium concentration in cell tissues within this range is possible with a novel calcium-selective reagent 15C5-774. The molecule of 15C5-774 consists of a near-infrared (NIR) chromophore (λ_max=774 nm) and a metal complexing moiety of benzo-15-crown-5. The reagent shows a strong calcium binding affinity in a 1:1 ratio and metal selectivity in the order Ca²⁺>Mg²⁺>Sr²⁺≈K⁺≈Na⁺>Zn²⁺>Li⁺. The high sensitivity is achieved by conducting absorption measurements in the NIR region where background interference from the biological matrix is low.     

Incorporating perylene moiety into poly(phenothiazine-co-bithiophene) backbone for higher charge transport

Low band gap pi-conjugated polymers composed of phenothiazine, bithiophene, and perylene moieties were prepared in high yields by using a palladium-catalyzed Suzuki coupling reaction. The polymers were characterized by NMR, gel permeation chromatography, and elemental analysis. The characterizations revealed that high-molecular weight (weight-average molecular weight up to 42,400 g/mol) polymers were thermally stable with a decomposition temperature in the region of 338-354 degrees C and their glass transition temperatures (Tg) ranging from 124 to 136 degrees C. All polymers demonstrated broad optical absorption in the region of 300-550 nm with efficient blue-green light emission. The absorption was broadened further (for ca. 50 nm) when the perylene moiety was incorporated. Cyclic voltammograms displayed that the p- and n-doping processes of all the polymers were partially reversible and that electrochemical band gaps were as low as -2.30 eV with the incorporation of a perylene moiety. The hole mobility of polymers was evaluated by using the space-charge-limited current model with a device structure of ITO/PEDOT:PSS/polymer/Ca. The results show that the incorporation of perylene is beneficial for improving the hole mobility of the conjugated polymers.     

Phosphorescent oxygen sensor with dendritic protection and two-photon absorbing antenna

Imaging oxygen in 3D with submicron spatial resolution can be made possible by combining phosphorescence quenching technique with multiphoton laser scanning microscopy. Because Pt and Pd porphyrin-based phosphorescent dyes, traditionally used as phosphors in biological oxygen measurements, exhibit extremely low two-photon absorption (2PA) cross-sections, we designed a nanosensor for oxygen, in which a 2P absorbing antenna is coupled to a metalloporphyrin core via intramolecular energy transfer (ET) with the purpose of amplifying the 2PA induced phosphorescence of the metalloporphyrin. The central component of the device is a polyfunctionalized Pt porphyrin, whose triplet state emission at ambient temperatures is strong, occurs in the near infrared and is sensitive to O2. The 2PA chromophores are chosen in such a way that their absorption is maximal in the near infrared (NIR) window of tissue (e.g., 700-900 nm), while their fluorescence is overlapped with the absorption band(s) of the core metalloporphyrin, ensuring an efficient antenna-core resonance ET. The metalloporphyrin-antenna construct is embedded inside the protecting dendritic jacket, which isolates the core from interactions with biological macromolecules, controls diffusion of oxygen and makes the entire sensor water-soluble. Several Pt porphyrin-coumarin based sensors were synthesized and their photophyics studied to evaluate the proposed design.     

ORMOCER®s for Optical Interconnection Technology

New inorganic-organic hybrid polymers (ORMOCER®s) for integrated optical and opto-electronic devices were synthesized by sol-gel processing of functionalized alkoxysilanes. Process parameters (catalyst, temperature etc.) were optimized to achieve highly reproducible low cost materials which are photopatternable even in higher layer thickness (presently 100 m within one step).The resulting materials have low optical losses at the most important wavelengths for telecommunications in the NIR range (0.3 dB/cm at 1320 nm, 0.6 dB/cm at 1550 nm) and a variety of additional advantageous properties for optical interconnection technology and production of opto-electronic devices: good wetting and adhesion on various substrates (e.g. glass, silicon and several polymers), low processing temperatures (post-bake at 150°C) and high thermal stability (decomposition at 270°C) compared to alternative opto-polymers for NIR applications. A further advantage is a tunable refractive index, which can be achieved by mixing different resins.