Synthesis of paramagnetic BODIPY dyes as new double (spin and fluorescence) sensors

Paramagnetic pyrroline and 1,2,3,6-tetrahydropyridine derivatives of BODIPY and their diamagnetic analogs have been synthesized and characterized as novel redox double sensor and cation sensitive reagents.     

双－全氟烷基氮氧自由基从取代苯甲醛的攫氢反应──用EPR方法建立取代基自旋离域参数σ的新尝试

Ｒ_ＦＮ（Ｏ　）Ｒ_Ｆ和Ｒ_ＦＮＯ的Ｆ１１３溶液在室温下与一系列的对位取代苯甲醛反应，得到稳定的对位取代苯甲酰基全氟烷基氮氧自由基。由△ａ_Ｎ和△ａ_Ｆ~β的σ单参数相关以及△ａ_Ｎ与σ和σ　双参数相关表明：极性效应是影响氟烷基酰基氮氧自由基中氮原子自旋密度变化的主要因素，而自旋离域效应的影响是很小的。     

Magnetic interactions in a series of paramagnetic Ln(III) complexes with a chelated imino nitroxide radical

The magnetic interactions in a new series of isostructural imino nitroxide radical lanthanide(III) complexes, [Ln(hfac)₃(IM2py)] (Ln = Gd–Yb: IM2py = 2-(2′-pyridyl)-4,5-dihydro-4,4,5,5-tetramethyl-1H-imidazoline-1-oxy; hfac = 1,1,1,5,5,5-hexafluoro-2,4-pentanedione), are examined by considering the intrinsic paramagnetic contribution of the Ln(III) ion from the corresponding [Ln(hfac)₃(pybzim)] with a diamagnetic pybzim(2-(2-pyridyl)benzimidazole) ligand; the Ln(III)–IM2py interaction being antiferromagnetic for the 4f⁷ to 4f¹³ Ln(III) complexes and negligibly small for the other complexes. This series is the first example reverse to the previous cases for the series of Ln–Cu or Ln–aminoxyl(NIT) radical (4,5-dihydro-4,4,5,5-tetramethyl-1H-imidazoline-3-oxide-1-oxy) complexes, other than only a few examples of semiquinone Ln complexes. This reverse nature of the magnetic interaction, as compared with the NIT complexes, validates the empirical approach by O. Kahn et al. [Inorg. Chem. 38 (1999) 3692; J. Am. Chem. Soc. 122 (2000) 3413] in the spin-coupled systems for a series of Ln(III) complexes.     

Properties and structures of porphyrexides

The molecular and crystal structures of porphyrexides, viz., 4-amino-2-imino-(1) and (Z)-2-amino-4-bromoimino-5,5-dimethyl-4,5-dihydro-1H-imidazole 1-oxyls (7), and their diamagnetic precursors were determined. Compound 1 is kinetically unstable because it is oxidized with atmospheric oxygen to form (E)-1,2-bis[1-amino-1-(cyanoimino)-2-methyl-propan-2-yl]diazene 1,2-dioxide. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 441–447, March, 2006.     

Esters of 4,5-dihydro-1H-imidazole-1-oxyl-3-oxide-carboximidic acid

Esters of 4,5-dihydro-1H-imidazole-1-oxyl-3-oxide-carboximidic acid were synthesized. Their structures and magnetic properties were investigated.     

Crystal Structure of Cu(hfac)2 Complexes with Organomercury Binitroxide

The organomercury biradical HgL₂ (L is deprotonated 4,4,5,5-tetramethyl-2-imidazoline-3-oxide-1-oxyl) is capable of performing the bridging function for design of multinuclear heterospin systems. This paper describes synthesis and crystal structure of HgL₂ and the first multinuclear complexes of Cu(hfac)₂ with HgL₂.     

Transformations of conjugated enamines of the imidazolidine 1-oxide series in the Vilsmeier-Haack reaction

In some cases, the reactions of enaminones of the imidazolidine 1-oxide series with the Vilsmeier reagent afford electrophilic substitution products containing the dimethyl-aminomethylene group. In an acidic medium, these products undergo either hydrolytic elimination of the dimethylaminomethylene moiety or hydrolysis of the latter to form the aldehyde group. The reaction of nitroenamine, which is a derivative of imidazolidine 1-oxide, with the Vilsmeier reagent produces furoxane, viz., the nitroxyl biradical. Reduction of the latter affords the dioxime biradical. Dedicated to the memory of Academician N. N. Vorozhtsov on the 100th anniversary of his birth. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1165–1170, June, 2007.     

Iminophosphanes: Unconventional Compounds of Main Group Elements

The large number of known stable compounds in which phosphorus has a low coordination number makes it clear that such compounds can no longer be regarded as “exotic” in main group chemistry. While the rich chemistry of P? C multiply bonded systems makes clear their affinity to their organic congeners, iminophosphanes in particular are also of increasing importance. The linkage of a phosphinidine fragment with an imine fragment via a multiple bond gives rise to a class of compounds with an unusually wide range of structural types. This in turn leads to a broad spectrum of chemical behavior which makes iminophosphanes extremely useful synthetic building blocks in organoelement chemistry.     

4-Amino-1-oxyl-2,2,6,6-tetramethylpiperidine-3-carboxylic acid (β-TOAC), the first spin-labelled, cyclic, chiral β-amino acid resolved in an enantiomerically pure state

Amination of 3-carboxymethyl-1-oxyl-2,2,6,6-tetramethyl-4-piperidone with (R)-α-methylbenzylamine, NaBH₃CN reduction of the resulting enamine and removal of the chiral auxiliary from the separated diastereoisomers, led to enantiomerically pure (3S,4S) and (3R,4R) methyl 4-amino-1-oxyl-2,2,6,6-tetramethylpiperidine-3-carboxylates.     

Structure of 2,4,4,5,5‐pentamethyl‐2‐imidazoline‐1‐oxyl‐3‐oxide

The crystal and molecular structures of the stable nitroxide radical 2,4,4,5,5pentamethyl2imidazoline1oxyl3oxide was determined. The N—O bond lengths are 1.279(2) and 1.280(2), respectively. The O^-—N⁺=C—N— O fragment is nearly planar with carbon atoms of the ethyl fragment that deviated from the O—N⁺=C—N—O plane by –0.204(5) and +0.176(5). The minimum intermolecular distance between the oxygen atoms of NO groups is 4.094.