Emission efficiency of diamine derivatives of tris[4,4,4-trifluoro-1-(2-thienyl)-1,3-butanediono]europium

Diamine derivatives of tris[4,4,4-trifluoro-1-(2-thienyl)-1,3-butanediono]europium were synthesized and characterized by NMR, IR and UV-vis spectroscopy. The emission efficiency and decay times of the produced Eu(III) coordination complexes in acetone solutions were measured upon ligand excitation. The effect of the amine ligands was studied and the relation between the emission and the structure of the synthesized compounds was discussed.     

双烷基及双（β－烷氧羰乙基）锡聚胺的合成及性质的研究

利用界面缩聚技术，将二烷基或二（烷氧羰已基）二氯化锡与有机二胺反应，制成了５８种有机锡聚胺大分子化合物，研究了部分聚胺对ＰＶＣ树脂热稳定性的影响，取得了有意义的结果。     

Efficient,Convenient and Mild Three Component Template Preparation and Characterization of Some New Schiff Base Complexes

A few kinds of novel Schiff base complexes have been prepared by three component reaction of the substituted hydroxyacetophenone with several aliphatic diamines and transition metals such as; Ni(II), Zn(II) and UO₂(II) under mild reaction conditions. The products have been afforded with excellent yields and appropriate reaction times. The structure of these ligands has been characterized by their IR, ¹H NMR, ¹³C NMR and MS spectral and physical data.     

Optimization of amine-terminated polyacrylonitrile synthesis and characterization

Amine-terminated PANs were prepared in two steps. The first step includes free radical polymerization of acrylonitrile (AN) using initiator pair of ammonium persulfate and sodium thiosulfate as redox system. In the second step, the amino groups were introduced through the reaction of polyacrylonitrile with excess of different diamines (10-fold) including ethylenediamine (EDA), hexamethylenediamine (HMDA) and octamethylenediamine (OMDA), to yield PAN–EDA, PAN–HMDA and PAN–OMDA, respectively. Optimization of the amine-terminated PANs synthesis was carried out at different temperatures (30–90 °C) and different time intervals (4–24 h). In addition, the introduction of the amino group was followed by the piperidine test and recording of the FT-IR spectra. All polymers were characterized by, ¹H NMR spectra, thermogravimetric analysis (TGA), and FT-IR spectra.     

Thermodynamic Data for the Formation of 1:1 and 2:1 Complexes of α,ω-Diamino Dihydrochlorides with 18-Crown-6 in Aqueous Solution

Calorimetric titrations are used to study the interactions between the crown ether 18-crown-6 and several α,ω-diamino dihydrochlorides in aqueous solution. These complexes are formed by ion-dipole interactions between the positively charged nitrogen atoms and the oxygen donor atoms of the crown ether. Depending on the experimental conditions, the formation of 1:1 or 2:1 complexes (ligand:diamines) can be studied. The solvation of the ligand and the amines are responsible for the observed thermodynamic values. The number of water molecules released during the reaction were calculated from the determined reaction entropies. Formation of 1:1 complexes distorts the solvation shell around the molecules. As a result, the number of solvent molecules released during the formation of the 2:1 complexes is slightly smaller than the number released from formation of the 1:1 complex. No experimental evidence is observed for the formation of complexes between one crown ether and two protonated amino groups.     

Asymmetric Synthesis of Vicinal Tetrasubstituted Diamines via Reductive Coupling of Ketimines Templated by Chiral Diborons

We herein describe the chiral diboron-templated asymmetric homocoupling of aryl alkyl ketimines, providing for the first time a series of chiral vicinal tetrasubstituted diamines with excellent ee values and good to high yields. The powerful and efficient diboron-participated [3,3]-sigmatropic rearrangement is successfully demonstrated by the homocoupling of a variety of ketimines thanks to the rational design and engineering of chiral diborons. Systematic DFT studies suggest that two chiral diborons adopt different conformational assembling strategies to couple the diboron template with ketimine substrates in their tight concerted transition states to ensure the excellent enantioselectivities. The synthetic value of chiral vicinal tetrasubstituted diamines is demonstrated by the asymmetric α-bromination of aliphatic aldehydes by employing a chiral vicinal tetrasubstituted diamine-based organocatalyst.     

An Efficient Synthesis of Chromeno[2,3‐d]pyrimidine‐2,4‐diones with a Nitroketene‐Aminal Moiety at C(5) by a One‐Pot Four‐Component Reaction

An efficient and novel synthesis of chromeno[2,3‐d]pyrimidine‐2,4‐dione derivatives with a nitroketene‐aminal moiety at C(5) via four‐component reaction of salicylaldehydes, barbituric acid, diamines, and 1,1‐bis(methylsulfanyl)‐2‐nitroethene in EtOH and in the presence of AcOH is reported. Easy performance, good yields, and easy purification are the main advantages of this method. All structures were confirmed by IR, MS, and ¹H‐ and ¹³C‐NMR, and by X‐ray crystal‐structure analyses. A plausible mechanism for this type of reaction is proposed (Scheme).     

Preparation of (1R,1′R)-1,1′-(anthracene-9,10-diyl)bis(2,2,2-trifluoroethanamine): a chiral diamine with low basicity

A new chiral diamine with low basicity was synthesized in enantiopure form. (1R,1′R)-1,1′-(Anthracene-9,10-diyl)bis(2,2,2-trifluoroethanamine) was obtained by means of several stereochemically controlled reactions. The structures of the title compound and several intermediates were studied.     

Synthesis of 1,2-Diamino-1-phenylpropane Diastereoisomers from <Emphasis Type="Italic">u</Emphasis>-<Emphasis Type="Italic">N</Emphasis>-Trifluoroacetyl-2-amino-1-phenylpropan-1-ol

Summary. A new simple procedure for the synthesis of diastereomeric 1,2-diamino-1-phenylpropanes starting from u-N-trifluoroacetyl-2-amino-1-phenylpropan-1-ol (N-trifluoroacetylnorephedrine) is described. The trifluoroacetyl protecting group was particularly suitable for the protection of the amino group in order to reduce side reactions.     

Chain-ring-chain tautomerism in 2-aryl-substituted hexahydropyrimidines and 1H-2,3-dihydroperimidines. Does it appear?

A series of 2-aryl substituted hexahydropyrimidines and perimidines were synthesized from aromatic aldehydes and substituted 1,3-propanediamines or 1,8-naphthalenediamine. The ¹H and ¹³C NMR spectra showed that 2-arylperimidines and 2-aryl-4,4,6-trimethylhexahydropyrimidines exist exclusively in ring forms even in DMSO solutions, whereas 2-aryl-4-methylhexahydropyrimidines undergo chain-ring-chain tautomerism with a good linear correlation between the ring-chain equilibrium constants (log K, where K=[ring]/[chain]) and the Hammett-Brown σ⁺ parameters of the aromatic substituents. 4,4,6-Trimethylhexahydropyrimidines underwent complete and irreversible ring opening in CF₃COOH solutions giving two different chain forms.