Incorporation of Designed Extended Chromophores into Amphiphilic 4-Helix Bundle Peptides for Nonlinear Optical Biomolecular Materials

Xu, Ting; Wu, Sophia P.; Miloradovic, Ivan; Therien, Michael J.; Blasie, J. Kent

doi:10.1021/nl062091p

Cited by 38 publications

(76 citation statements)

References 37 publications

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“…These chromophores evince significant PZn–(polypyridyl)metal electronic interactions, display unusual dependences of the sign and magnitude of the hyperpolarizability upon the incident irradiation frequency, and exhibit substantial β λ values at telecommunications-relevant wavelengths. 16,21−23,26,41,42,47 …”

Section: Introductionmentioning

confidence: 99%

Large Hyperpolarizabilities at Telecommunication-Relevant Wavelengths in Donor–Acceptor–Donor Nonlinear Optical Chromophores

et al. 2016

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Octopolar D2-symmetric chromophores, based on the MPZnM supermolecular motif in which (porphinato)zinc(II) (PZn) and ruthenium(II) polypyridyl (M) structural units are connected via ethyne linkages, were synthesized. These structures take advantage of electron-rich meso-arylporphyrin or electron-poor meso-(perfluoroalkyl)porphyrin macrocycles, unsubstituted terpyridyl and 4′-pyrrolidinyl-2,2′;6′,2″-terpyridyl ligands, and modulation of metal(II) polypyridyl-to-(porphinato)zinc connectivity, to probe how electronic and geometric factors impact the measured hyperpolarizability. Transient absorption spectra obtained at early time delays (tdelay < 400 fs) demonstrate fast excited-state relaxation, and formation of a highly polarized T1 excited state; the T1 states of these chromophores display expansive, intense T1 → Tn absorption manifolds that dominate the 800–1200 nm region of the NIR, long (μs) triplet-state lifetimes, and unusually large NIR excited absorptive extinction coefficients [ε(T1 → Tn) ∼ 105 M–1 cm–1]. Dynamic hyperpolarizability (βλ) values were determined from hyper-Rayleigh light scattering (HRS) measurements, carried out at multiple incident irradiation wavelengths spanning the 800–1500 nm spectral domain. The measured βHRS value (4600 ± 1200 × 10–30 esu) for one of these complexes, RuPZnRu, is the largest yet reported for any chromophore at a 1500 nm irradiation wavelength, highlighting that appropriate engineering of strong electronic coupling between multiple charge-transfer oscillators provides a critical design strategy to realize octopolar NLO chromophores exhibiting large βHRS values at telecom-relevant wavelengths. Generalized Thomas–Kuhn sum (TKS) rules were utilized to compute the effective excited-state-to-excited-state transition dipole moments from experimental linear-absorption spectra; these data were then utilized to compute hyperpolarizabilities as a function of frequency, that include two- and three-state contributions for both βzzz and βxzx tensor components to the RuPZnRu hyperpolarizability spectrum. This analysis predicts that the βzzz and βxzx tensor contributions to the RuPZnRu hyperpolarizability spectrum maximize near 1550 nm, in agreement with experimental data. The TKS analysis suggests that relative to analogous dipolar chromophores, octopolar supermolecules will be likely characterized by more intricate dependences of the measured hyperpolarizability upon irradiation wavelength due to the interactions among multiple different β tensor components.

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Section: Introductionmentioning

confidence: 99%

Large Hyperpolarizabilities at Telecommunication-Relevant Wavelengths in Donor–Acceptor–Donor Nonlinear Optical Chromophores

et al. 2016

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“…These structures manifest significant inter-pigment electronic interactions, display unusual dependences of the sign and magnitude of hyperpolarizability on incident irradiation frequency, and exhibit extraordinarily large β λ values at telecommunications-relevant wavelengths. 18,25,29-31,45,47,48…”

Section: Introductionmentioning

confidence: 99%

The Roles of Molecular Structure and Effective Optical Symmetry in Evolving Dipolar Chromophoric Building Blocks to Potent Octopolar Nonlinear Optical Chromophores

et al. 2011

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A series of mono-, bis-, tris-, and tetrakis-(porphinato)zinc(II) (PZn)-elaborated ruthenium(II) bis(terpyridine) (Ru) complexes has been synthesized in which an ethyne unit connects the macrocycle meso carbon atom to terpyridyl (tpy) 4-, 4′-, and 4″-positions. These supermolecular chromophores, based on the ruthenium(II) [5-(4′-ethynyl-(2,2′;6′,2″-terpyridinyl))-10,20-bis(2′,6′-bis(3,3-dimethyl-1-butyloxy)phenyl)porphinato]zinc(II)-(2,2′;6′,2″-terpyridine) 2+ bishexafluorophosphate (RuPZn) archetype, evince strong mixing of the PZn-based oscillator strength with ruthenium terpyridyl charge resonance bands. Potentiometric and linear absorption spectroscopic data indicate that for structures in which multiple PZn moieties are linked via ethynes to a [Ru(tpy) 2 ] 2+ core, little electronic coupling is manifest between PZn units, regardless of whether they are located on the same or opposite tpy ligand. Congruent with these experiments, pump-probe transient absorption studies suggest that the individual RuPZn fragments of these structures exhibit, at best, only modest excited-state electronic interactions that derive from factors other than the dipole-dipole interactions of these strong oscillators; this approximate independent character of the component RuPZn oscillators enables fabrication of NLO multipoles with extraordinary hyperpolarizabilities.Dynamic hyperpolarizability (β λ ) values and depolarization ratios (ρ) were determined from hyper-Rayleigh light scattering (HRS) measurements carried out at an incident irradiation wavelength (λ inc ) of 1300 nm. The depolarization ratio data provide an experimental measure of chromophore optical symmetry; appropriate coupling of multiple charge-transfer oscillators produces structures having enormous averaged hyperpolarizabilities (β HRS values), while evolving (PF 6 ) 2 possessing a β HRS value at 1300 nm more than a factor of three larger than that determined for any chromophore having octopolar symmetry examined to date. Because NLO octopoles possess omnidirectional NLO responses while circumventing the electrostatic interactions that drive bulk-phase centrosymmetry for NLO dipoles at high chromophore concentrations, the advent of octopolar NLO chromophores having vastly superior β HRS values at technologically important wavelengths will motivate new experimental approaches to achieve acentric order in both bulk-phase and thin film structures.

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“…Inspection of fiducial structures have guided the design of such systems, where Zn is coordinated with appropriate side-chain ligands ( e.g ., histidine) and hydrophobic residues are patterned so as to stabilize a helical bundle. In addition, such designed α-helical proteins can be displayed in oriented molecular arrays at interfaces 34–36. Many of these systems examined thus far have fluctuating tertiary structures, however, and likely do not have the geometric complementarity and highly structured physico-chemical protein-porphyrin interactions observed in natural proteins 33,35.…”

Section: Introductionmentioning

confidence: 99%

Computational Design and Elaboration of a de Novo Heterotetrameric α-Helical Protein That Selectively Binds an Emissive Abiological (Porphinato)zinc Chromophore

et al. 2010

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The first example of a computationally de novo designed protein that binds an emissive abiological chromophore is presented, in which a sophisticated level of cofactor discrimination is pre-engineered. This heterotetrameric, C2-symmetric bundle, AHis:BThr, uniquely binds (5,15-di[(4-carboxymethyleneoxy)phenyl]porphinato)zinc [(DPP)Zn] via histidine coordination and complementary noncovalent interactions. The A2B2 heterotetrameric protein reflects ligand-directed elements of both positive and negative design, including hydrogen-bonds to second-shell ligands. Experimental support for the appropriate formulation of [(DPP)Zn:AHis:BThr]2 is provided by UV/visible and circular dichroism spectroscopies, size exclusion chromatography, and analytical ultracentrifugation. Time-resolved transient absorption and fluorescence spectroscopic data reveal classic excited-state singlet and triplet PZn photophysics for the AHis:BThr:(DPP)Zn protein (kfluorescence = 4 × 108 s−1; τriplet = 5 ms). The A2B2 apoprotein has immeasurably low binding affinities for related [porphinato]metal chromophores that include a (DPP)Fe(III) cofactor and the zinc metal ion hemin derivative [(PPIX)Zn], underscoring the exquisite active site binding discrimination realized in this computationally designed protein. Importantly, elements of design in the AHis:Bthr protein ensure that interactions within the tetra-α-helical bundle are such that only the heterotetramer is stable in solution; corresponding homomeric bundles present unfavorable ligand-binding environments, and thus preclude protein structural rearrangements that could lead to binding of (porphinato)iron cofactors.

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Incorporation of Designed Extended Chromophores into Amphiphilic 4-Helix Bundle Peptides for Nonlinear Optical Biomolecular Materials

Cited by 38 publications

References 37 publications

Large Hyperpolarizabilities at Telecommunication-Relevant Wavelengths in Donor–Acceptor–Donor Nonlinear Optical Chromophores

Large Hyperpolarizabilities at Telecommunication-Relevant Wavelengths in Donor–Acceptor–Donor Nonlinear Optical Chromophores

The Roles of Molecular Structure and Effective Optical Symmetry in Evolving Dipolar Chromophoric Building Blocks to Potent Octopolar Nonlinear Optical Chromophores

Computational Design and Elaboration of a de Novo Heterotetrameric α-Helical Protein That Selectively Binds an Emissive Abiological (Porphinato)zinc Chromophore

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