Electronic spectroscopy, photophysical properties, and emission quenching studies of an oxidatively robust perfluorinated platinum porphyrin

The highly electron-deficient, beta-octafluorinated meso-tetrakis(pentafluorophenyl)-porphyrin (H(2)F(28)TPP) was metalated with platinum to afford the oxidatively robust luminophore [PtF(28)TPP], and its X-ray structure shows that the porphyrin core exists in a slightly saddle-shaped conformation. The absorption spectrum of [PtF(28)TPP] in CH(2)Cl(2) displays a near-UV Soret band (B) at 383 nm (epsilon = 2.85 x 10(5) dm(3) mol(-1) cm(-1)) and two visible Q(1,0) and Q(0,0) bands at 501 (epsilon = 1.45 x 10(4) dm(3) mol(-1) cm(-1)) and 533 (epsilon = 1.36 x 10(4) dm(3) mol(-1) cm(-1)) nm, respectively. These absorption bands of [PtF(28)TPP] are blue-shifted from those in [PtF(20)TPP] (390, 504, and 538 nm, respectively) and [PtTPP] (401, 509, and 539 nm, respectively). Excitation of [PtF(28)TPP] (complex concentration = 1.5 x 10(-6) mol dm(-3)) in dichloromethane at the Soret or Q(1,0) or Q(0,0) band gave a phosphorescence with peak maximum at 650 nm (lifetime = 5.8 micros) and a weak shoulder at 712 nm. Both the emission lifetime and quantum yield vary with solvent polarity, and plots of tau versus E(K) and Phi versus E(K) (where E(K) is the empirical solvent polarity parameter based on the hypsochromic shift of the longest wavelength absorption of the [Mo(CO)(4)[(C(5)H(4)N)HC[double bond]NCH(2)C(6)H(5)]] complex with increasing solvent polarity; see: Kamlet, M. J.; Abboud, J. L. M.; Taft, R. W. Prog. Phys. Org. Chem. 1981, 13, pp 485-630) show linear correlation, indicating that the emission is sensitive to the local environment/medium. Electrochemical studies on [PtF(28)TPP] by cyclic voltammetry showed no porphyrin-centered oxidation at potential < or = 1.5 V versus Ag/AgNO(3), demonstrating that [PtF(28)TPP] is more resistant toward oxidation than [PtF(20)TPP] (E(1/2) = 1.33 V) and [PtTPP] (E(1/2) = 0.97 V). The porphyrin-centered reduction of [PtF(28)TPP] occurs at -0.75 and -1.18 V, which is anodically shifted from those at -1.06 and -1.55 V in [PtF(20)TPP], and -1.51 V in [PtTPP], respectively. The excited-state reduction potential of [PtF(28)TPP] is estimated to be 1.49 V versus Ag/AgNO(3). Over 97% of the emission intensity of [PtF(28)TPP] was retained after irradiation with a high power mercury arc lamp (500 W) for 14 h, compared to 90% and 12% for [PtF(20)TPP] and [PtTPP], respectively; hence, [PtF(28)TPP] exhibits superior photostability. Quenching of the emission of [PtF(28)TPP] by oxygen, alcohol, catechol, and butylamine reveals that [PtF(28)TPP] is an oxidatively robust material with medium-sensitive photoluminescence properties.     

Self-assembled oligonucleotide-polyester dendrimers

A new approach to the controlled synthesis of multicomponent dendrimers is presented, in which three oligonucleotide-dendron conjugates were synthesized using solid phase techniques and hybridized to create a second generation polyester dendrimer with DNA as a core and bearing two types of peripheral functional groups.     

Microwave spectrum of CIS chlorine nitrite,CIONO

The metastable intermediate product, CIONO, which is formed from gaseous CINO and Cl₂O at about 203 K, has been detected by microwave spectroscopy. The rotational constants and the inertial defects for the ³⁵Cl and ³⁷Cl species establish that the observed spectrum is that of planar cis CIONO.     

Metal Ion Dependent Binding and Nuclease Activity of Hexaazacyclophane

The HAPP-Fe complex was more active than HAPP-Cu complex in cleavage of DNA in the presence of dithiothreitol and hydrogen peroxide. In contrast, the HAPP-Cu complex was found to bind more strongly with λ-DNA, whereas the HAPP-Fe binds weakly. It was shown that the metal ion complexed with HAPP ligand can influence the binding and cleaving activity due to the ability of the ligand to undergo geometrical tautomerization.     

天然物6—正戊基吡喃—2—酮（6PP）的全合成

6-正戊基吡喃-2-酮（1）首先被确认为桃子香精中的一个组分[1]，而后又发现是一系列真菌，如Trichodermaharzianum[2]、Trichodermaviride[3]等的代谢物．6PP具有典型的可可香味[4]，并具有抗真菌的性质，它显著地抑制诸如Verticilliumdahliae、V．fungicolaPyra－noechaetalysopersici等多种真菌的生长．空气中高浓度的6PP可影响莴苣种子的萌芽、生长[5]．我们以廉价易得的糠醛（2）为原料，经5步反应合成了天然物1：仪器：FT－170SX型红外光谱仪，涂膜法；FT－80A或BrukerAM400型核磁共振仪，TMS为内标，CDCl3作溶剂，ZAB－HS…     

含二羟基二苯酮热致液晶共聚酯的合成与表征（Ⅵ）──含二羟基二苯酮热致液晶共聚酯结晶结构的X射线衍射研究

以广角Ｘ－射线衍射（ＷＡＸＤ）对含二羟基二苯酮（ＢＨＰ）、对羟基苯甲酸（ＰＨＢＡ）、对苯二甲酸（ＴＰＡ）、问苯二酚（ＲＥＳ）的系列热致液品共聚酯进行了较为深入的研究，详细讨论了不同组成的共聚酯的结晶结构、结晶度、结晶颗粒大小等等。     

Free Radical‐Induced and Pd(II) Complexes‐Catalyzed Poly(norbornene) Formation

The reactions of norbornene polymerization were catalyzed by Pd(CH₃CN)₄(BF₄)₂ ( 1 ), AIBN ( 2 ), and [{(2,6‐C₆H₃(ⁱPr)₂)N=C(Me)}₂Pd(Me)(CH₃CN)][BF₄] ( 3 ) without using methylalumoxane (MAO). These poly(norbornene)s are readily soluble in organic solvents such as toluene, dichloromethane and tetrahydrofuran. According to the NMR data, the end group of PNA resulting from the AIBN process is found from THF. The PNT resulting from the catalyst ( 1 ) shows bi‐models of GPC bands (M_n= 4236 and 66317), two glass transition temperatures (T_g = 72.7 and 201.5 °C), as well as two decomposition temperatures (Td = 337 and 460 °C).