This paper reports the two-photon absorbing and orange-red fluorescence emitting properties of a series of new 2,1,3-benzothiadiazole (BTD)-based D-pi-A-pi-D-type and star-burst-type fluorescent dyes. In the D-pi-A-pi-D-type dyes 1-6, a central BTD core was connected with two terminal N,N-disubstituted amino groups via various pi-conjugated spacers. The star-burst-type dyes 8 and 10 have a three-branched structure composed of a central core (benzene core in 8 and triphenylamine core in 10) and three triphenylamine-containing BTD branches. All the BTD-based dyes displayed intense orange-red color fluorescence in a region of 550-689 nm, which was obtained by single-photon excitation with good fluorescent quantum yield up to 0.98 as well as by two-photon excitation. Large two-photon absorption (TPA) cross-sections (110-800 GM) of these BTD dyes were evaluated by open aperture Z-scan technique with a femtosecond Ti/sapphire laser. The TPA cross-sections of D-pi-A-pi-D-type dyes 2-6 with a benzene, thiophene, ethene, ethyne, and styrene moiety, respectively, as an additional pi-conjugated spacer are about 1.5-2.5 times larger than that of 1c with only a benzene spacer. The TPA cross-sections significantly increased in three-branched star-burst-type BTDs 8 (780 GM) with a benzene core and 10 (800 GM) with a triphenylamine core, which are about 3-5 times larger than those of the corresponding one-dimensional sub-units 9 (170 GM) and 11 (230 GM), respectively. The ratios of sigma/e(pi) between three-branched and one-dimensional dyes were 6.5:3.8 (for 8 and 9) and 6.0:4.0 (for 10 and 11), which are larger than those predicted simply on the basis of the chromophore number density (1:1), according to a cooperative enhancement of the two-photon absorbing nature in the three-branched system.

This paper reports the unique influence of added [60]fullerene on the gelation ability of Zn(II) porphyrin appended cholesterols 5a − d. At 5 °C 5a with a (CH2)2 spacer gelated aromatic hydrocarbons such as benzene, toluene, and p-xylene (2.55 × 10-2 mol dm-3), whereas at 20 °C these transparent gels were changed into sols. In the presence of [60]fullerene (0.5 equiv) the gel structure of 5a was maintained even at 20 °C in these solvents. A similar gel stabilization effect was also observed for 5c, which has a (CH2)4 spacer. In contrast, 5b and 5d with a (CH2)3 and a (CH2)5 spacer, respectively, could not gelate these solvents even in the presence of [60]fullerene. Detailed spectroscopic studies established that the reinforcement of the gel structure is rationalized in terms of the intermolecular Zn(II) porphyrin−[60]fullerene interaction, which is possible only in the gel phase. When the concentration of 5a and 5c in toluene was kept constant (0.20 mol dm-3), the sol−gel phase transition temperature increased with an increase in the number of equivalents of added [60]fullerene up to 0.5 equiv and then maintained constant above 0.5 equiv. These results consistently support the view that two porphyrin planes in 5a and 5c interact with one [60]fullerene molecule to form a 2:1 Zn(II) porphyrin/[60]fullerene sandwich complex. The distinct bathochromic shift of the Soret absorption band, which was found in the gel samples of 5a and 5c in the presence of [60]fullerene in toluene, indicates that the intermolecular electronic interaction does exist between the Zn(II) porphyrin moiety and the [60]fullerene in the gel phase. The circular dichroism (CD) spectra of the gel samples of 5a and 5c in the presence of [60]fullerene showed the reproducible and reliable Cotton effects around the Soret absorption band. The observed CD intensities were much stronger than those obtained from the sol samples of 5a and 5c in the absence of [60]fullerene. The results suggest that the Zn(II) porphyrin moieties in 5a and 5c are enforced to orient chirally in the gel phase by the interaction with [60]fullerene. In particular, the highly stabilized gel sample of 5a obtained by the addition of [60]fullerene showed a negative excitation-coupling-type CD spectrum, indicating that the porphyrin chromophores are oriented in an anticlockwise direction. The aggregate structures formed in the organogel systems of 5a and 5c were also discussed by means of infrared spectroscopic measurements and scanning electron microscopy observations. Thus, this is the first example for organogel stabilization utilizing a Zn(II) porphyrin−[60]fullerene interaction.

Novel donor-pi-bridge-acceptor-pi-bridge-donor (D-pi-A-pi-D) type 2,1,3-benzothiadiazole fluorescent dyes connected to the N,N-diarylamino terminus via various type pi-conjugate spacers exhibits large two-photon absorption cross-sections and high fluorescent quantum yields in orange-red color.

Foetomaternal alloimmune thrombocytopenia (FMAIT) occurs when maternal antibodies of an antigen-negative mother cause destruction of sensitized foetal platelets. In Caucasian populations, 6-12% of human platelet antigen (HPA)-1a-negative women develop anti-HPA-1a, and the incidence of clinically affected cases is estimated to be 10-20% of immunized women. This study was performed in order to elucidate the rate of maternal immunization, incidence of FMAIT and the likely outcome of the condition in Asians. Excluding two or more pregnancies during the period, serum samples from 24 630 pregnant women, mainly Japanese, were screened for antibodies against platelet alloantigens by means of mixed passive haemagglutination (MPHA) (Anti-HPA-MPHA, Olympus, Tokyo). Antibodies were detected in 0.91% (223/24 630) of the women's samples and the immunization rate was correlated with the number of pregnancies. Antibody specificity included anti-HPA-4b (49), anti-HPA-5a (three), anti-HPA-5b (168), anti-HPA-4b + 5b (one) and anti-Nak(a) (CD36) (two). No alloimmunization was observed within the HPA-1, HPA-2, HPA-3 or HPA-6 systems. Among HPA-4b- or HPA-5b-negative women, 24% or 14% estimated, respectively, had antibodies and 26% (10/38) or 10% (12/125) of neonates, respectively, born to these mothers developed thrombocytopenia. Two neonates born to mothers having anti-HPA-4b developed generalized purpura. No cases of intracranial bleeding or death due to FMAIT were recorded. Generalized purpura due to FMAIT occurs in one in 9359 (95% CI: 1 in 77 519-1 in 2591) pregnancies solely because of HPA-4b incompatibility.

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