RESUMEN

Di(p-benzi)[40]decaphyrin(1.0.0.0.0.1.0.0.0.0) BF2 complex and tris(p-benzi)[60]pentadecaphyrin(1.0.0.0.0.1.0.0.0.0.1.0.0.0.0) BF2 complex were synthesized by Suzuki-Miyaura coupling of α,α'-diborylated tetrapyrrole BF2 -complex with 1,4-diiodobenzene. Bis-BF2 complex was converted to bis-PdII complex via its free base. Macrocycles bis-BF2 and tris-BF2 complex take Möbius topology but are nonaromatic, since the macrocyclic conjugation is disrupted by the locally aromatic 1,4-phenylene units. In contrast, bis-PdII complex is a weakly Hückel 38π-aromatic macrocycle as evinced by its red-shifted, enhanced, and structured Q-like bands and a small electrochemical HOMO-LUMO gap. Interestingly, one 1,4-pheylene part of bis-PdII complex takes a quinonoidal distorted structure and the other takes a usual benzene structure in a figure-eight conformation with Hückel topology.

RESUMEN

The light-transmissive properties of a solid-state tetrathiafulvalene radical cation-bis(trifluoromethanesulfonyl)imide, 1-C5 ⋅+ ⋅ NTf2 - , underwent instantaneous changes in the short-wave infrared (SWIR) region (1000-2500 nm) upon exposure to solvent vapor or the application of mechanostress at room temperature. The initial solid state of 1-C5 ⋅+ ⋅ NTf2 - exhibited strong absorption in the near-infrared (NIR; 700-1000 nm) and SWIR regions, whereas the absorption in the SWIR region was significantly diminished in the stimulated state induced by dichloromethane vapor. Upon cessation of vapor stimulation, the solid state spontaneously and promptly reverted to its original state, characterized by absorption bands in the NIR/SWIR region. Moreover, the SWIR absorption was absent upon the application of mechanical stress using a steel spatula. The reversal was fast and occurred within 10 s. These changes were visualized using a SWIR imaging camera under 1450-nm light irradiation. Experimental investigations demonstrated that the transparency to the SWIR light in the solid states was modulated through significant structural transformations of the associated radical cations, with transitions between columnar and isolated π-dimer structures under ambient and stimulated conditions, respectively.

RESUMEN

Near-IR (NIR) organic dyes have been widely utilized in life sciences and materials science. Herein we report an unusually large NIR solvatochromism of monohydroxybenziphthalocyanine, an analogue of 18π-electron aromatic phthalocyanine in which a single isoindoline unit is replaced with a phenol ring. The solvatochromism is attributed to deprotonation of the phenol moiety in highly polar solvents, leading to the generation of a strongly NIR-absorptive 18π-electron aromatic quinoidal monoanion.

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RESUMEN

A liquescent dihydrophenazine radical cation, 1.+ ⋅NTf2 - , showed drastic changes in near-infrared (near-IR) transparency and opaqueness through hysteretic phase transitions with no measurable degradation of the compound even under aerated conditions. During the heating and slow cooling process (0.5 K min-1 ), its electronic and magnetic properties were altered clearly and repeatedly changed between solid and liquid states. The liquid state was transparent to near-IR light (940 nm), but the solid state was opaque, despite both samples exhibiting a similar green color under room light. Additionally, the liquid state was changed to a glass state under a fast cooling process (2-10 K min-1 ). UV/Vis/near-IR and electron spin-resonance spectroscopy revealed that these drastic changes were attributable to the dynamic dissociation and association of a π-dimer structure for 1.+ accompanying with the solid-liquid phase transitions even under the neat conditions.

RESUMEN

Large-area 2D cocrystals with strong near-infrared (NIR) absorption have been designed and prepared. Driven by the intermolecular charge-transfer (CT) interactions, zinc tetraphenylporphyrin (donor) and C60 (acceptor) self-assemble into a NIR cocrystal with absorption wavelength up to 1080 nm. By tailoring the growth solvents and processes, the cocrystal morphologies can be tuned from 1D nanowires, 2D nanosheets to large-area 2D cocrystal films with length reaching several millimeters. Owing to the highly ordered donor-acceptor arrangement, the CT absorption in the 2D cocrystals is enhanced and is comparable to singlet absorption. The uniform 2D cocrystals, with enhanced CT absorption in the NIR region, displays a high responsivity of 2424 mA W-1 to NIR light and a fast response time of 0.6 s. The excellent device performance is attributed to the generation of long-lived free charge carriers as revealed by transient absorption spectroscopy and optimization of device configuration.

RESUMEN

Despite the widespread use of laser lithotripsy to fragment kidney stones in vivo, there is a lack of robust artificial stone models to replicate the behavior of human stones during lithotripsy procedures. This need for accurate stone models is particularly important as novel laser technologies are introduced in the field of lithotripsy. In this work, we present a method to prepare composite materials that replicate the properties of human kidney stones during laser lithotripsy. Their behavior is understood through the lens of near-IR spectroscopy and helps to elucidate the mechanism of laser lithotripsy in kidney stone materials.

RESUMEN

A cocrystal strategy with a simple preparation process is developed to prepare novel materials for near-infrared photothermal (PT) conversion and imaging. DBTTF and TCNB are selected as electron donor (D) and electron acceptor (A) to self-assemble into new cocrystals through non-covalent interactions. The strong D-A interaction leads to a narrow band gap with NIR absorption and that both the ground state and lowest-lying excited state are charge transfer states. Under the NIR laser illumination, the temperature of the cocrystal sharply increases in a short time with high PT conversion efficiency (η=18.8 %), which is due to the active non-radiative pathways and inhibition of radiative transition process, as revealed by femtosecond transient absorption spectroscopy. This is the first PT conversion cocrystal, which not only provides insights for the development of novel PT materials, but also paves the way of designing functional materials with appealing applications.

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RESUMEN

A series of novel iodinated NO2 -substituted aza-BODIPYs have been synthesized and characterized. Highly desirable photophysical and photochemical properties were induced in NO2 -substituted aza-BODIPYs by iodination of the pyrrole rings. In particular, high values of singlet oxygen quantum yields (ΦΔ ) ranging from 0.79 to 0.85 were measured. The photooxygenation process proceeds via a Type II mechanism under the experimental conditions applied. The compounds studied exhibited an absorption band within the so-called "therapeutic window", with λmax located between 645 nm to 672 nm. They were non-fluorescent at room temperature with excited singlet-state lifetimes within the picosecond range as measured by femtosecond transient absorption. Nanosecond laser flash photolysis experiments revealed T1 →Tn absorption spanning from ca. 400 nm to ca. 500 nm and allowed determination of the triplet-state lifetimes. The estimated triplet lifetimes (τT ) in deaerated acetonitrile ranged between 2.74 µs and 3.50 µs. As estimated by CV/DPV measurements, all iodinated aza-BODIPYs studied exhibited one irreversible oxidation and two quasi-reversible reductions processes. Estimation of the EHOMO gave the value of -6.06 to -6.26 eV while the ELUMO was found to be located at ca. -4.6 eV. Thermogravimetric (TGA) analysis revealed that iodinated aza-BODIPYs were stable up to approximately 300 °C. All compounds studied exhibit high photostability in toluene solution.

RESUMEN

A meso-meso ß-ß ß-ß triply linked subporphyrin dimer 6 was synthesized by stepwise reductive elimination of ß-to-ß doubly PtII -bridged subporphyrin dimer 9. Dimer 6 was characterized by spectroscopic and electrochemical measurements, theoretical calculations, and picosecond time-resolved transient absorption spectroscopy. X-ray diffraction analysis reveals that 6 has a bowl-shaped structure with a positive Gaussian curvature. Despite the curved structure, 6 exhibits a remarkably red-shifted absorption band at 942 nm and a small electrochemical HOMO-LUMO gap (1.35 eV), indicating an effectively conjugated π-electronic network.

RESUMEN

W18O49 with a tunable oxidation state was prepared by addition of NaNO3 or NaBH4 as a redox agent in the solvothermal system. The addition of redox agents has no influence on the crystallization of W18O49. The obtained W18O49 structures keep their morphology as a bundle of nanowires with a regular hexagonal on the cross-section. W18O49 exhibits strong valence-dependent absorption features in the near-IR region. Reduced W18O49 with more W5+ has a higher concentration of oxygen vacancies, which enhances the localized surface plasmon resonance effect. Reduced W18O49 exhibits a high photothermal conversion efficiency of 59.6 % and has good photothermal stability.

RESUMEN

The physical properties of doped multifunctional compounds are commonly tuned by controlling the amount of dopants, but this control is limited because all the properties are influenced simultaneously by this single parameter. Here, we present a strategy that enables the fine-tuning of a specific combination of properties by controlling the reduction of dopants. The feasibility of this approach was demonstrated by optimizing the near-IR photoluminescence of strontium titanate SrTiO3 :Ni for potential applications in biomedicine for a range of absorbance in the visible/near-IR region. We discussed how material properties, such as luminescence, conductivity, or photocatalytic properties can be designed by carefully controlling the ratio of dopants in different oxidation states.

RESUMEN

The facile synthesis of Group 9 Rh(III) porphyrin-aza-BODIPY conjugates that are linked through an orthogonal Rh-C(aryl) bond is reported. The conjugates combine the advantages of the near-IR (NIR) absorption and intense fluorescence of aza-BODIPY dyes with the long-lived triplet states of transition metal rhodium porphyrins. Only one emission peak centered at about 720 nm is observed, irrespective of the excitation wavelength, demonstrating that the conjugates act as unique molecules rather than as dyads. The generation of a locally excited (LE) state with intramolecular charge-transfer (ICT) character has been demonstrated by solvatochromic effects in the photophysical properties, singlet oxygen quantum yields in polar solvents, and by the results of density functional theory (DFT) calculations. In nonpolar solvents, the Rh(III) conjugates exhibit strong aza-BODIPY-centered fluorescence at around 720 nm (ΦF =17-34 %), and negligible singlet oxygen generation. In polar solvents, enhancements of the singlet-oxygen quantum yield (ΦΔ =19-27 %, λex =690 nm) have been observed. Nanosecond pulsed time-resolved absorption spectroscopy confirms that relatively long-lived triplet excited states are formed. The synthetic methodology outlined herein provides a useful strategy for the assembly of functional materials that are highly desirable for a wide range of applications in material science and biomedical fields.

RESUMEN

Design, synthesis, characterization, and photodynamic activity of mitochondria specific asymmetric ZnPc-Rh B conjugates are described. Conjugation of asymmetric ZnPc-OH chromophores 3a and 3b with rhodamine B via the corresponding DIC-activated ester gave the desired near IR-absorbing asymmetric ZnPc-Rh B conjugates 1a and 1b. Conjugates 1a and 1b were shown to produce singlet oxygen upon illumination in DMSO, MeOH and THF. Fluorescence aggregation studies of the dyes 1a, 1b, 3a and 3b in DMSO and phosphate buffered saline (PBS) solution showed that conjugates 1a and 1b were less aggregated compared to the corresponding non-conjugates 3a and 3b suggesting that incorporation of Rh B lowered aggregation of the conjugates in the PBS solution. The four dyes studied have logD7.4 values between 2.31 and 2.48, with the sulfur-containing conjugate 1b being the most hydrophobic. All the dyes showed negligible dark toxicity when colon 26 cells were treated with 5 µM of the dyes while 10-15% cell death was observed for dye concentrations of 15 µM. Illumination (700±40 nm, 45 J/cm(2), 15 min) of the cells ([dye]=15 µM) gave 70% cell death for ZnPc-Rh B conjugates 1a and 1b while no killing for non-conjugates 3a and 3b suggesting that the incorporation of the Rh B in the photosensitizer lowered the aggregation and subsequently improved cellular uptake and phototoxicity.

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