A Red-Light-Driven CO-Releasing Complex: Photoreactivities and Excited-State Dynamics of Highly Distorted Tricarbonyl Rhenium Phthalocyanines.

A complex comprising one [Re(CO)3 ]+ unit and a phthalocyanine (Pc) ligand (Re1 Pc) is shown to function as a photo-induced CO-releasing molecule (photoCORM) in the presence of O2 and a coordinative solvent under irradiation with red light, which can deeply penetrate living tissues. Transient absorption spectroscopic measurements indicate very short excited-state lifetimes and ultrafast intersystem crossing for Re1 Pc and Re2 Pc, which contains two [Re(CO)3 ]+ units. The excited-state properties are ascribed to efficient spin-orbit coupling and large Franck-Condon factors originating from the complexes' distorted structures, that is, unsymmetric coordination of [Re(CO)3 ]+ unit(s), one of which was confirmed by single-crystal X-ray analysis of a symmetrically substituted Pc with two [Re(CO)3 ]+ units. Re1 Pc represents a promising red-light-driven photoCORM that can be applied in biological environments or therapeutic applications.

The CRP-family transcriptional regulator DevH regulates expression of heterocyst-specific genes at the later stage of differentiation in the cyanobacterium Anabaena sp. strain PCC 7120.

Heterocysts are terminally differentiated cells of filamentous cyanobacteria, which are specialized for nitrogen fixation. Because nitrogenase is easily inactivated by oxygen, the intracellular environment of heterocysts is kept microoxic. In heterocysts, the oxygen-evolving photosystem II is inactivated, a heterocyst-specific envelope with an outer polysaccharide layer and an inner glycolipid layer is formed to limit oxygen entry, and oxygen consumption is activated. Heterocyst differentiation, which is accompanied by drastic morphological and physiological changes, requires strictly controlled gene expression systems. Here, we investigated the functions of a CRP-family transcriptional regulator, DevH, in the process of heterocyst differentiation. A devH-knockdown strain, devH-kd, was created by replacing the original promoter with the gifA promoter, which is repressed during heterocyst differentiation. Although devH-kd formed morphologically distinct cells with the heterocyst envelope polysaccharide layer, it was unable to grow diazotrophically. Genes involved in construction of the microoxic environment, such as cox operons and the hgl island, were not upregulated in devH-kd. Moreover, expression of the nif gene cluster was completely abolished. Although CnfR was expressed in devH-kd, the nif gene cluster was not induced even under microoxic conditions. Thus, DevH is necessary for the establishment of a microoxic environment and induction of nitrogenase in heterocysts.

Case report: Perilymphatic fistula from a round window microfissure.

A microfissure near the round window niche is an anatomical structure that communicates between middle ear and the ampulla of the posterior semicircular canal. It has been suggested that the microfissure can cause inner ear symptoms; however, the etiology has not yet been confirmed clinically. We report, to our knowledge, the first case of microfissure with complaint of hearing loss and vertigo and improvement in hearing after surgical sealing of the microfissure. A 50-year-old man complained of hearing disturbance, tinnitus with flowing-water sound in the left ear, and a floating sensation upon pushing the left tragus. He had moderate sensorineural hearing loss (43.3 dB) in the left ear for 3 days. His hearing worsened and he complained of severe vertigo. An exploratory tympanotomy was performed 8 days after onset. A microfissure and accumulation of clear fluid in the floor of the round window niche were detected, and leakage point was packed with connective tissue. One month after surgery, his hearing (20.0 dB) and disequilibrium had improved. The inner ear symptoms improved after the surgery in this case, suggesting that the microfissure might have caused the symptoms.

Novel method for preparing stable near-infrared absorbers: a new phthalocyanine family based on rhenium(i) complexes.

Rational design of near-infrared (NIR) absorbing molecules is crucial for developing photofunctional materials. Here, we synthesized dinuclear and mononuclear Re(i) tricarbonyl phthalocyanine complexes that exhibit a sharp intense Q band in the NIR region. The unsymmetric coordination of electron-deficient metal unit(s) concomitantly produced a remarkable red shift of the Q band and improved the tolerance of the phthalocyanine ring to oxidation. This study presents a simple and effective strategy for the construction of NIR absorbers with high stability.