Ce@C(82) is isolated by high-performance liquid chromatography (HPLC) and the cage symmetry is determined as C(2)(v)() by measuring the (13)C NMR spectra of its anion. The (13)C NMR peaks of [Ce@C(82)](-) show temperature-dependent shifts ascribed to the f electron remaining on the Ce atom. Both Ce@C(82) and [Ce@C(82)](-) are silent in electron spin resonance spectroscopy (ESR) because of the highly anisotropic g matrix as well as of the fast relaxation process originating from the orbital angular momentum of the f electron. This is the complementary relationship to the observation of the paramagnetic shift in (13)C NMR. [Ce@C(82)](-) has lower stability in air than [La@C(82)](-).

Photolysis and thermolysis of diazirines have been widely used to produce carbenes. 1 Bonneau and Liu have reported that these reactions yield not only a singlet carbene but also a diazo compound as an intramolecular rearrangement product. 2 The nature of the specific substituents on the diazirine determines the formation of the corresponding diazomethane as an intermediate, which may or may not be observed. 3 These authors also reported on the quantum yields of the formation of carbene and diazo compounds derived from the photolysis of diazirines by means of laser flash photolysis. 2 Numerous chemical transformations have been developed since the isolation of C 60 in preparatively useful quantities. 4 C 60 has a unique reactivity, which differs significantly from that of classical planar aromatics. 5 C 60 reacts with diazomethane to yield fulleroid. 5d,6 Carbene generated from the thermolysis of precursors such as diazirines, 7 sodium trichloroacetate, 8 cyclopropene, 9 oxadiazole, 10 and tosylhydrazone 11 adds onto C 60 , affording methanofullerene. 4 These differences might be useful in differentiating whether carbene or diazo compound is involved as the reactive intermediate. In this context, we have carried out the photolysis of diazirine in the presence of C 60 .Our report demonstrates that C 60 acts as a mechanistic probe for the formation of carbene and diazo compound in the photolysis of diazirine. As well, our experiment offers the first redox data of methanofullerene and fulleroid bearing the same substituent at the bridging carbon atom on the C 60 moiety.Irradiation of a benzene solution of 2-adamantane-2,3′-[3H]-diazirine (1, 2.5 × 10 -4 M) and C 60 (2.5 × 10 -3 M) with a highpressure mercury arc lamp (cutoff < 300 nm) at 15°C in a Pyrex tube resulted in the formation of the corresponding adduct C 60 -Ad (2) in 80% yield, which was purified by preparative HPLC with a GPC column. Adduct 2 can be readily separated into two isomers, 2a and 2b, by preparative HPLC with a Buckyprep column (Scheme 1). The isomeric ratio of 2a and 2b is 49/51. FAB mass spectrometry of 2a and 2b gives a molecular ion peak (C 70 H 14 requires m/z 854) at m/z 858-854, as well as a peak for C 60 at m/z 724-720, which arises from the loss of the adamantyl group. The UV-visible absorption spectra of 2a and 2b are virtually identical to that of C 60 , except for a subtle difference in the 400-650 nm region. These results suggest that 2a and 2b retain the essential electronic and structural character of C 60 . The UV-visible absorption spectrum of 2a has an absorption at 434 nm, which is a characteristic feature of a 6,6-adduct of C 60 . 12 The spectral data of 1 H and 13 C NMR and 2D NMR (HMQC and HMBC) clearly suggest that 2a has C 2V symmetry. 13 Meanwhile, the analysis of 1 H and 13 C NMR(HMQC and HMBC) has offered crucial evidence for the identification of C s symmetry of 2b as a 5,6-adduct of C 60 . 14 We carried out density functional calculations at the BLYP/ 3-21G level for 2a and 2b with the Gaussian 98 program. 15 ...

To identify potential regulators of photoassimilate partitioning, we screened for rice mutant plants that accumulate high levels of starch in the leaf blades, and a mutant line leaf starch excess 1 (LSE1) was obtained and characterized. The starch content in the leaf blades of LSE1 was more than 10-fold higher than that in wild-type plants throughout the day, while the sucrose content was unaffected. The gene responsible for the LSE1 phenotype was identified by gene mapping to be a gene encoding α-glucan water dikinase, OsGWD1 (Os06g0498400), and a 3.4-kb deletion of the gene was found in the mutant plant. Despite the hyperaccumulation of starch in their leaf blades, LSE1 plants exhibited no significant change in vegetative growth, presenting a clear contrast to the reported mutants of Arabidopsis thaliana and Lotus japonicus in which disruption of the genes for α-glucan water dikinase leads to marked inhibition of vegetative growth. In reproductive growth, however, LSE1 exhibited fewer panicles per plant, lower percentage of ripened grains and smaller grains; consequently, the grain yield was lower in LSE1 plants than in wild-type plants by 20~40%. Collectively, although α-glucan water dikinase was suggested to have universal importance in leaf starch degradation in higher plants, the physiological priority of leaf starch in photoassimilate allocation may vary among plant species.

Starch accumulated in rice (Oryza sativa L.) stems before heading as nonstructural carbohydrates (NSCs) is reported to be important for improving and stabilising grain yield. To evaluate the importance of stem starch, we investigated a retrotransposon (Tos17) insertion rice mutant lacking a gene encoding a large subunit of ADP-glucose pyrophosphorylase (AGP) called OsAGPL1 or OsAPL3. The AGP activity and starch contents of the mutant were drastically reduced in the stem (i.e. leaf sheath and culm) but not in the leaf blade or endosperm. This starch reduction in the leaf sheaths of the mutant was complemented by the introduction of wild-type OsAGPL1. These results strongly suggest that OsAGPL1 plays a principal role in stem starch accumulation. Field experimentations spanning 2 years revealed that the mutant plants were shorter than the wild-type plants. Moreover, the tiller number and angle were larger in the mutant plants than the wild-type plants, but the dry weight at heading stage was not different. The grain yield was slightly lower in control plots without shading treatment. However, this difference increased substantially with shading. Therefore, stem starch is indispensable for normal ripening under low irradiance conditions and probably contributes to the maintenance of appropriate plant architecture.

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In rice (Oryza sativa L.), tiller angle – defined as the angle between the main culm and its side tillers – is one of the important factors involved in light use efficiency. To clarify the relationship between tiller angle, gravitropism and stem-starch accumulation, we investigated the shoot gravitropic response of a low stem-starch rice mutant which lacks a large subunit of ADP-glucose pyrophosphorylase (AGP), called OsAGPL1 and exhibits relatively spread tiller angle. The insensitive gravitropic response exhibited by the mutant led us to the conclusion that insensitivity of gravitropism caused by stem-starch reduction splayed the tiller angle. Furthermore, since another AGP gene called OsAGPL3 was expressed at considerable levels in graviresponding sites, we generated a double mutant lacking both OsAGPL1 and OsAGPL3. The double mutant exhibited still lower stem-starch content, less sensitive gravitropic response and greater tiller angle spread than the single mutants. This indicated that the expansion of the tiller angle caused by the reduction in starch level was intense according to the extent of the reduction. We found there were no significant differences between the double mutant and wild-type plants in terms of dry matter production. These results provided new insight into the importance of stem-starch accumulation and ideal plant architecture.