Exploration of triplet-triplet annihilation based photon upconversion (TTA-UC) in aqueous environments faces difficulty such as chromophores insolubility and deactivation of excited triplets by dissolved oxygen molecules. We propose a new strategy of biopolymer-surfactant-chromophore coassembly to overcome these issues. Air-stable TTA-UC with a high upconversion efficiency of 13.5% was achieved in hydrogel coassembled from gelatin, Triton X-100 and upconverting chromophores (triplet sensitizer and emitter). This is comparable to the highest UC efficiency observed to date for air-saturated aqueous UC systems. Moreover, this is the first example of air-stable TTA-UC in the form of hydrogels, widening the applicability of TTA-UC in biological applications. The keys are two-fold. First, gelatin and the surfactant self-assemble in water to give a developed hierarchical structure with hydrophobic domains which accommodate chromophores up to high concentrations. Second, thick hydrogen-bonding networks of gelatin backbone prevent O inflow to the hydrophobic interior, as evidenced by long acceptor triplet lifetime of 4.9 ms. Air-stable TTA-UC was also achieved for gelatin with other nonionic surfactants (Tween 80 and Pluronic f127) and Triton X-100 with other gelling biopolymers (sodium alginate and agarose), demonstrating the versatility of current strategy.

Inspired by the bicontinuous ionic-network structure of ionic liquids (ILs), we developed a new family of photofunctional ILs which show efficient triplet energy migration among contiguously arrayed ionic chromophores. A novel fluorescent IL, comprising an aromatic 9,10-diphenylanthracene 2-sulfonate anion and an alkylated phosphonium cation, showed pronounced interactions between chromophores, as revealed by its spectral properties. Upon dissolving a triplet sensitizer, the IL demonstrated photon upconversion based on triplet-triplet annihilation (TTA-UC). Interestingly, the TTA-UC process in the chromophoric IL was optimized at a much lower excitation intensity compared to the previous nonionic liquid TTA-UC system. The superior TTA-UC in this IL system is characterized by a relatively high triplet diffusion constant (1.63×10(-6) cm(2) s(-1)) which is ascribed to the presence of ionic chromophore networks in the IL.

The first example of green (λ > 500 nm)-to-ultraviolet (λ < 400 nm) triplet–triplet annihilation-based photon upconversion sensitized by lead halide perovskite nanocrystals is achieved.

Visible‐to‐ultraviolet (vis‐to‐UV) triplet‐triplet annihilation based photon upconversion (TTA‐UC) is achieved in a non‐volatile chromophoric ionic liquid (IL) for the first time. A novel IL is synthesized by combining UV‐emitting anion 4‐(2‐phenyloxazol‐5‐yl)benzenesulfonate (PPOS) and trihexyltetradecylphosphonium cation (P66614). The nanostructured organization of chromophoric anions is demonstrated by synchrotron X‐ray and optical measurements. When the IL is doped with a triplet sensitizer tris(2‐phenylpyridinato)iridium(III) (Ir(ppy)3), the visible‐to‐UV TTA‐UC with a relatively low threshold excitation intensity of 61 mW cm−2 is achieved. This is due to a large triplet diffusion coefficient in the IL (1.4×10−7 cm2 s−1) as well as a high absorption coefficient 15 cm−1 and a long PPOS triplet lifetime of 1.55 ms, all implemented in the condensed IL system. This work demonstrates the unique potential of ILs to control chromophore arrangements for desired functions.

There is an urgent demand for developing functional bioplastics that carry renewable energy production and replace conventional synthetic plastics. Here we report a simple one-step approach to create bioplastics with...

A novel chromophoric ionic liquid (IL) with two-dimensional (2D) nanostructural order is developed, and its structure-property relationship is investigated by harnessing photon upconversion based on triplet energy migration. An ion pair of 9,10-diphenylanthracene-2-sulphonate (DPAS) and asymmetric quaternary phosphonium ion exhibited both ionic crystal (IC) and supercooled IL phases at room temperature. Single crystal X-ray analysis of the IC phase showed an alternate alignment of polar (ionic) and non-polar (non-ionic) layers, and this layered structure was basically maintained even in the IL phase. The diffusion length of triplet excitons in the IL phase, obtained by the analysis of upconverted emission in succession to triplet-triplet annihilation (TTA), is larger than the domain size estimated from powder X-ray analysis. This suggests that triplet excitons in chromophoric ILs can diffuse over the nanostructured domains.

Inspired by the bicontinuous ionic-network structure of ionic liquids (ILs), we developed an ew family of photofunctional ILs whichs howe fficient triplet energy migration among contiguously arrayed ionic chromophores.Anovel fluorescent IL, comprising an aromatic 9,10-diphenylanthracene 2-sulfonate anion and an alkylated phosphonium cation, showed pronounced interactions between chromophores,a s revealed by its spectral properties.U pon dissolving at riplet sensitizer,the IL demonstrated photon upconversion based on triplet-triplet annihilation (TTA-UC). Interestingly,t he TTA-UC process in the chromophoric IL was optimizedatamuch lower excitation intensity compared to the previous nonionic liquid TTA-UC system. The superior TTA-UC in this IL system is characterized by ar elatively high triplet diffusion constant (1.63 10 À6 cm 2 s À1 )which is ascribed to the presence of ionic chromophore networks in the IL.

An ionic liquid (IL) composed of 9-anthracenecarboxylate anion and ammonium cation possessing three diethylene glycol chains shows phototriggered dimerization of anthracence chromophores. It causes segregation and crystallization of protonated 9-anthracenecarboxylic acid dimer, which is associated with the concurrent liberation of the free amine in the IL. This work provides a new molecular design for photoresponsive ILs, whose first application for site-selective photopatterning is demonstrated.Ionic liquids (ILs) have attracted considerable interest from many researchers because of their unique physical and chemical properties, which are tunable depending on their constituents. 13One of the evolving areas in this field is the introduction of mesoscopic interfaces 4,5 for developing novel interfacial phenomena. 6,7 In this regard, ILs containing π-conjugated chromophores are attractive as photofunctional soft materials that show new applications such as condensed luminescent materials 810 and solar thermal storage. 11 We have recently reported the photoliquefaction of ionic crystals to ILs by employing cationic azobenzene derivatives covalently modified with three flexible diethylene glycol chains in the ammonium head group. 11 Photon energy was effectively stored not only as the conformational energy of the azobenzene unit but also as the latent heat of crystallization, where the integration of self-assembly phenomena and photoresponsive ILs opened the doors to the phase crossover chemistry. 11Here, we describe a new photoresponsive IL that shows photoinduced crystallization phenomena. It is formed from a well-known Brønsted acid (9-anthracenecarboxylic acid, A-COOH) 12,13 and a Brønsted base having three flexible diethylene glycol chains (tris[2(2methoxyethoxy)ethyl]amine, 1). This integration based on acidbase neutralization gives a chromophoric IL [1-H] +