Synthesis of mono-O-alkylated homooxacalix[3]arene and a protection–deprotection strategy for homooxacalix[3]arene

The regioselective synthesis of mono-O-alkylated homooxacalix[3]arene is accomplished for the first time. The synthetic route relies on two key steps: (i) a facile protection of two OH groups at the lower rim of the homooxacalix[3]arene and (ii) the deprotection of 9- anthrylmethyl groups via the Pd/C-catalyzed hydrogenation under atmospheric hydrogen. An efficient protection- deprotection strategy for the functionalization of homooxacalix[ 3]arene is presented

Synthesis and structures of O-anthrylmethyl-substituted hexahomotrioxacalix[3]arenes

O-Alkylation of 7,15,23-tri-tert-butyl-25,26,27-trihydroxy-2,3,10,11,18,19-hexahomo-3,11,19-trioxacalix[3]arene (1H₃) with 9-chloromethylanthracene 5 was carried out under different reaction conditions. Variation of the number of anthrylmethyl group introduced at the phenolic rim of hexahomotrioxacalix[3]arene 1H₃ was achieved through selective O-alkylation using stoichiometric amounts of 9-chloromethylanthracene 5 in acetone to afford the mono-O-alkylated product 2H₂An, the di-O-alkylated product 3HAn₂ and the tri-O-alkylated product partial-cone-4An₃, respectively. Interestingly, by using an acetone/benzene (1:1 v/v) mixed solvent system, the cone-4An₃ was successfully synthesized. These results suggest that the solvent can also control the conformation of the O-alkylation products. The possible reaction routes of the cone-4An₃ and partial-cone-4An₃ are also discussed

A pyrene-functionalized triazole-linked hexahomotrioxacalix[3]arene as a fluorescent chemosensor for Zn²⁺ ions

A new pyrenyl appended hexahomotrioxacalix[3]arene L featuring 1,2,3-triazole linkers was synthesized as a fluorescent chemosensor for Zn²⁺ in mixed aqueous media. It exhibited high affinity toward Zn²⁺, and the monomer and excimer emission of the pyrene moieties could be adjusted. The binding stoichiometry of the L·Zn²⁺ complex was determined to be 1:1, and the association constant (Ka) was found to be 7.05 × 10⁴ M⁻¹. The binding behavior with Zn²⁺ has been confirmed by ¹H NMR spectroscopic analysis

Bayesian Approach to Find a Long-Term Trend in Erratic Polarization Variations Observed in Blazars

We developed a method to separate a long-term trend from observed temporal variations of polarization in blazars using a Bayesian approach. The temporal variation of the polarization vector is apparently erratic in most blazars, while several objects occasionally exhibited systematic variations, for example, an increase of the polarization degree associated with a flare of the total flux. We assume that the observed polarization vector is a superposition of distinct two components, a long-term trend and a short-term variation component responsible for short flares. Our Bayesian model estimates the long-term trend which satisfies the condition that the total flux correlates with the polarized flux of the short-term component. We demonstrate that assumed long-term polarization components are successfully separated by the Bayesian model for artificial data. We applied this method to photopolarimetric data of OJ 287, S5 0716+714, and S2 0109+224. Simple and systematic long-term trends were obtained in OJ 287 and S2 0109+224, while no such a trend was identified in S5 0716+714. We propose that the apparently erratic variations of polarization in OJ 287 and S2 0109+224 are due to the presence of the long-term polarization component. The behavior of polarization in S5 0716+714 during our observation period implies the presence of a number of polarization components having a quite short time-scale of variations.Comment: 12 pages, 7 figures, accepted for publication in PAS

Synthesis and evaluation of a novel fluorescent sensor based on hexahomotrioxacalix[3]arene for Zn²+ and Cd²+

A novel type of selective and sensitive fluorescent sensor having triazole rings as the binding sites on the lower rim of a hexahomotrioxacalix[3]arene scaffold in a cone conformation is reported. This sensor has desirable properties for practical applications, including selectivity for detecting Zn²⁺ and Cd²⁺ in the presence of excess competing metal ions at low ion concentration or as a fluorescence enhancement type chemosensor due to the cavity of calixarene changing from a ‘flattened-cone’ to a more-upright form and inhibition of PET. In contrast, the results suggested that receptor 1 is highly sensitive and selective for Cu²⁺ and Fe³⁺ as a fluorescence quenching type chemosensor due to the photoinduced electron transfer (PET) or heavy atom effect

Formation and implementation of the Jasak Lama system in the early Qing period

This paper clarifies how the Qing administrative system for Tibetan Buddhist monks, called the Jasak Lama system, was formed and implemented during the early Qing period. Jasak Lama (Man. jasak i lama) is a professional rank established by the Qing dynasty among Tibetan Buddhist monks. Jasak means \u27administrator\u27 in Mongolian (Mon. ǰasaγ), and had also been used to refer to the head of the Mongol banner during that period. To administrate the Tibetan Buddhist community and their activities in the Qing dynasty, the Jasak Lama system was generally applied to the Tibetan Buddhist monks staying inside the Qing territory. Preceding studies have pointed out that this system was introduced in four main areas during the Shun-zhi era (1643-1661), Beijing, Mukden, Hohhot, and Hure Banner, before being spread to other places. However, this paper clarifies that administrator court lamas had already been evidenced during the Hontaiji era (1626-1643), and it can be regarded of as the initial step of the Jasak Lama system. This paper also clarifies that the Qing dynasty adopted an "inner and outer two Kuren (*a Manchurian term that means \u27house\u27) structure" in its earliest stages. Subsequently, after the Qing\u27s conquest of Beijing, the Qing dynasty extended the Jasak Lama system\u27s coverage along with the expansion of the Qing\u27s territory, and eventually adopted a \u27multi-Kuren structure\u27. This paper proves that the monks who played a leading role in the Jasak Lama system and took active roles in Qing dynasty policies concerning Tibetan Buddhism in the early period had an intricate relationship with some monasteries of the Bsam-blo group in the eastern part of the Amdo area. As such, the valuable activities of the eastern Amdo monks as forerunners laid the foundation for the Jasak Lama system in the Qing dynasty

Morphology of the Neurocentral Junction during Postnatal Growth of Alligator (Reptillia, Crocodylia).

The two main parts of a vertebra, the centrum and neural arch, form independently during early developmental stages in nearly all vertebrates, and they typically fuse together in later growth stages. Fusion between centrum and neural arch is the result of ossification of a thin cartilage layer (neurocentral synchondrosis) between them. The timing of neurocentral fusion varies considerably within the vertebral column and among species, especially in archosaurian reptiles, and may be related to changes in body size and/or locomotion. Despite the importance of neurocentral fusion to our understanding of archosaur evolution, basic information about this process and how it changed through time remains poorly understood. In this dissertation, morphology of neurocentral sutures and vertebrae in crocodilians (Reptilia, Archosauria) is explored. In Chapter 2, the detailed cell- and tissue-level morphology of neurocentral sutures in the vertebrae of Alligator mississippiensis is documented. In chapter 3, complexity of neurocentral sutures are quantified, and changes related to differences in vertebral position, ontogenetic age, and phylogeny are examined. In Chapter 4, allometric changes in vertebrae of Alligator are quantified and investigated in relation to key ontogenetic events. As seen in some craniofacial bones in various vertebrates, neurocentral fusion may affect changes in relative size and shape of certain vertebral structures (e.g., centrum, neural spine, transverse processes, neural canal) during growth. In chapter 5, data examined in crocodilians (chapters 2–4) are applied to various fossil archosaurs from the Early Mesozoic to investigate the origin and evolutionary significance of two unique features of neurocentral sutures, delayed neurocentral fusion and complex neurocentral sutures.Ph.D.GeologyUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/78850/1/ikejiri_1.pd