Syntheses Of Heterocyclic Dyes And Studies On Their Relative Properties

Pyridine-2,6-dione based heterocyclic dyes have been studied quite intensively because of their significant advantages on sublimation fastness,brightness of shade and brilliant dyeing properties.However,the pyridine-2,6-dione based disperse dyes can only be used under the acidic condition in the dyeing process and the color of dyes fades quickly under the basic condition.In order to overcome the shortcoming,we believe that the replacement of the acidic hydroxyl by certain alkali-stable groups should improve the pH stability of resultant dyes in terms of dye-molecule design.So the synthetic strategy of functional group transformation(FGT)is proposed in this article to prepare new types of pyridone based heterocyclic azo dyes,in which the pH stability is significiantly increased via modifying the acidic hydroxyl of pyridine-2,6-dione precusors with 3-methoxypropan-1-amine.In order to expand the study of pyridine-2,6-dione based metal complexes,bis(pyridine-2,6-dione)dyes with more coordination sites,stronger coordination abilities and more possible deprotonated states have been investgated in this paper as well as their related metal complexes.In addition,the ?max of these bis(pyridine-2,6-dione)dyes not only demonstrate red-shifted to 576 nm but also the metal-ion mediated regioselective complexation is achieved for our bis(pyridine-2,6-dione)dyes depending on the competition between coordination abilities of metal ions and strength of six-membered hydrogen-bonding ring involving the central hydrazone proton.In addition,a fabric indicator based on benzisothiazole/pyrazolone bi-heterocyclic dye is achieved in our study.At last,a series of novel photochromic styryl compounds bearing different push-pull substituents have been synthesized from 2-formylthiophene based heterocyclic azo dyes.Interestingly,the photoisomerization of the double bond(C=C)can be achieved through irradiation with visible light.In total,on the one hand,this paper provides an effective method for designing new FGT heterocyclic dyes including thiophene azo dyes.On the other hand,this paper expands the cooridination chemistry of pyridione based multidentate ligands.Specifically,the main work of this paper is divided into the following six parts:Chapter 1:Introduction.Here we focus on the critical concepts and theories,difficulties and shortcomings in the field of dye compounds and pave the way for latter research thoughts and results.Firstly,we describle the developments and frontier applications of dye chemistry.At the same time,we discussed the disperse dyes including their concepts,types and developments.Among the disperse dyes,heterocyclic azo dyes are one of the most important research objects because they are easily synthesized.They have been widely used in traditional textile industry due to their wide variety of color shades and brilliant colors.Besides,they have potencial wide applications on non-linear optics,optical data storage,two proton absorptions and dye-sensitized solar cells.At last,we introduce the significances and approaches of this topic upon the previous works.Chapter 2:Increased pH stability via functional group transformation from acidic hydroxyl to basic secondary amine for a series of pyridone based heterocyclic dyes.Synthetic strategy of functional group transformation has been utilized to modify the acidic hydroxyl(-OH)of a series of pyridone based heterocyclic dyes into basic secondary amine(-NHCH2CH2CH2OCH3),so as to improve the color instability of hydrazone dyes under the basic condition.Namely,five pairs of 6-(3-methoxypropylamino)pyridin-2-one based azo dyes have been synthesized showing significantly increased pH stability,which can be verified by corresponding UV-Vis spectra.Successful configuration transformation from the-NH-N=unit in the hydrazone dyes into the-N=N-one in the resultant azo dyes is believed to obstruct the proton transfer between the pyridone and azo/hydrazone units(azo-hydrazone tautomerism),thereby enhancing the pH stability especially under the alkaline condition.In addition,different N-substituted groups at the pyridone ring and push-pull electronic substituted groups at the phenyl ring have been selected to make spectral and structural comparisons before and after the functional group transformation.Chapter 3:Extremely high pH stability for a class of heterocyclic azo dyes having the common N2,N6-bis(3-methoxypropyl)pyridine-2,6-diamine coupling component.A series of N2,N6-bis(3-methoxypropyl)pyridine-2,6-diamine azo dyes,prepared by coupling 2,6-bis((3-methoxypropyl)amino)-4-methylnicotinonitrile and diazotized substituted anilines with distinguishable electron push-pull abilities,have been described in this paper.The new dyes undergoing double functional group transformation(FGT)show extremely high pH stability compared to corresponding mono FGT dyes,which could be ascribed to the introduction of the second 3-methoxypropylamino group forming the new pyridine-2,6-diamine backbone.It is noted that the unusual transformation from D-?-A to A-?-D system has been verified for our multi-substituted phenyl-azo-pyridine FGT products.The adjustment of electron-donating and electron-withdrawing phenyl and pyridine substituted groups narrows the discrepancy of electron push-pull capabilities for dizao and coupling components,which makes possible the transformation for roles of donor and acceptor.It is believed that the achievement of extremely high pH stability for pyridine-2,6-diamine based heterocyclic azo dyes is regarded as a useful exploration for designing new FGT modified pyridone dyes.Chapter 4:pH-induced azo-keto and azo-enol tautomerism for 6-(3-methoxypropylamino)pyridin-2-one based thiophene azo dyes.The synthetic strategy of combining functional group transformation(FGT)and post-modification(PM)is proposed to prepare two new types of 2-amino-3-cyano-4-chloro-5-formylthiophene based heterocyclic azo dyes with mono and double 3-methoxypropan-1-amine substituted pyridine components,where the terminal aldehyde radical of the 2-formylthiophene moiety is extended into imine,acetal or ?,?-unsaturated cyanoacetic ester group.The evaluation of pH stability of the mono FGT products indicates that the basic stability is depended upon the?-conjugated system of the diazo components by comparing our synthesized thiophene and azobenzene based dyes,in which better electron delocalization may facilitate the proton transfer within molecule resulting in poor stability towards base.Furthermore,the intra-ring azo-keto(?)azo-enol tautomerism in the coupling components is suggested to explain the appearance of five isoabsorptive points in their pH-titration experiments.In contrast,all the N2,N6-bis(3-methoxypropyl)pyridine-2,6-diamine based azo dyes exhibit extremely high pH stability no matter what diazo components are used,because no proton accepting sites are present after the double FGT.It is also found that the synthesized thiophene heterocyclic dyes exhibit a large color gamut after PM.For example,the maximum absorption wavelength(?max)is significantly red-shifted from 496 nm in the acetal compound to 590 nm in the cyanoacetic ester terminated dye.Chapter 5:Metal-ion mediated regioselective complexation for bis(pyridine-2,6-dione)dyes with different deprotonated states.Bis(pyridine-2,6-dione)dyes with different pyridine N-tails are first used as the multidentate ligands to prepare a series of Ca?,Na?,Cu? and Ni? complexes.1H NMR and UV-Vis spectral as well as X-ray single-crystal analyses reveal that they have mononuclear,dinuclear and one-dimensional structures bearing bis(pyridine-2,6-dione)based ligands with more coordination sites,distinguishable coordination modes and deprotonated states.In addition,the transformations from the hydrazone form to deprotonated hydrazone form and deprotonated azo form have been observed before and after metal-ion complexation.pH-controlled syntheses and pH-induced conversion have been achieved for a pair of alkali-earth metal Ca?complexes,which can be verified by(1)their different colors and crystalline forms in syntheses;(2)different chemical shifts of pyridine methyl groups in the 1H NMR spectra;(3)the presence of an isosbestic point during the pH-titration experiments;(4)comparisons on the coordination bond lengths and dihedral angles between the two pyridine rings for related complexes.It is very interesting to mention that regioselective complexation has been found for bis(pyridine-2,6-dione)based ligands,which could be explained by the competition between coordination abilities of metal ions and strength of intramolecular hydrogen-bonding ring involving the central hydrazone proton.Chapter 6:A fabric indicator based on benzisothiazole/pyrazolone bi-heterocyclic dye.A new bi-heterocyclic dye has been synthesized by reacting 5-nitrobenzo[c]isothiazol-3-amine with 5-methyl-2-phenyl-2,4-dihydro-3H-pyrazol-3-one.It is noted that the dye shows strong solvatochromism in five organic solvents with distinguishable polarity.More interestingly,distinct colors are observed on six types of fibers,i.e.CT,C,N,T,A and W(Cellulose Acetate,Cotton,Nylon,Polyester,Acrylic and Wool),under different pH values,in which the clear borderline between adjacent fabrics is found on multifibres after the reductive cleaning by Na2S2O4/NaOH.The unique tinting behavior makes this dye a good candidate for the monocomponent fiber indicator especially for the blended fibers.It is believed that the possible reason for above-mentioned solvatochromism and fabric discoloration arises from the active proton migration within its bi-heterocyclic backbone,which could be induced by the distinguishable polarity of organic solvents and microenvironments of fibers.Chapter 7:Heterocyclic azobenzene induced for tuning the syntheses of olefin-azo compounds through S-? interaction.A series of novel styryl-azo compounds containing cis-/trans-isomers have been prepared via post-modification of 2-formylthiophene based heterocyclic azo dye.In addition,compounds with different configurations can be obtained seperatly by introducing push-pull electronic substituted groups.It is believed that the strong S-? interaction plays an important role on the formation of viarous configurations,which can be proved by corresponding X-ray single-crystal structures.Interestingly,the photoisomerization of the C=C double bond can be achieved through irradiation with visible light,leading to trans-isomer from cis-isomer.Moreover,the trans-isomer is very stable at room temperature and can return to cis-isomer under heating conditions.The photochromic performances make these synthesized styryl-azo compounds have a potencial application on photoswiches.