Trifluoroacetic acid in the synthesis of thiolcarbamates and s-methyl alkanethioates

The major products of the reaction of 2-bromohexanoic acid with methyl thiocyanate in trifluoroacetic acid are S-methyl 2-bromohexanethioate (II) (55% yield), S-methyl 2,2,2-trifluoroethanethioate (IV) (31% yield), N-trifluoro-acetyltrifluoroacetamide (V) (11% yield), and N-trifluoroacetyl-S-methylthiol-carbamate (III) (29% yield). N-2-Bromohexanoyl-S-methylthiolcarbamate (I), N-2-bromohexanoyltrifluoroacetaraide (VI), 2-thiapropioamide(VII), and S-methyl hex-anethioate (VIII) are also formed in minor amounts.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1, pp. 195–198, January, 1991.     

毛萼乙素及其一类物的化学选择性合成

本文首次报道从冬凌草甲素(3)经6步或7步反应改造成毛萼乙素(1)和脱氢毛萼甲素(2), 总产率分别为11和10%, 经4步或5步反应改造成新化合物14-羟基毛萼乙素(4)和14-羟基脱氢毛萼甲素(5), 总产率分别为57和49%。     

Ion flotation behaviour of thirty-one metal ions in mixed hydrochloric/nitric acid solutions

The ion flotation of 31 metal ions in hydrochloric/nitric acid solution with the cationic surfactant cetylpyridinium chloride was investigated. A 25-ml portion of 0.27-2.87 x 10(-4)M metal ion and 1.8-6.0 x 10(-4)M cetylpyridinium chloride solution in 0.17-3.4M acid mixture ([HCl]:[HNO(3)] = 2.4:1) was subjected to flotation in a cell, 22.5 cm high and 4.0 cm in diameter, for 5 min, with nitrogen bubbles. Ir(IV), Pt(IV), Ge(IV), Sn(IV), Bi(III), Au(III), Tl(III), Pd(II) and Sn(II) were floated from solution in 95-100% yield; Ru(III), Rh(III), Ir(III), Hg(II), Ag(I) and Tl(I) were partly floated, while Cr(VI), Ti(IV), Zr(IV), Ga(III), In(III), Fe(III), Sb(III), Al(III), Mn(II), Fe(II), Co(II), Ni(II), Cu(II), Zn(II), CD(II) and Pb(II) were floated with less than 20% yield. The flotation behaviour of these metal ions in the mixed acid system was compared with that in hydrochloric acid. The flotation is more efficient in the mixed acid system.     

Preparation and some reactions of 3,9-dichloro-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5] undecane-3,9-disulfide

3, 9-Dichloro-2, 4, 8, 10-tetraoxa-3, 9-diphosphaspiro[5. 5]undecane-3,9-disulfide (I), has been synthesized by treating a dimethylacetamide solution of 2, 4, 8, 10-tetraoxa-3,9-diphosphaspiro[5. 5]undecane-3, 9-disulfide (III) with carbon tetrachloride. A number of other known methods for converting dialkyl phosphorothioites to thiophosphorochloridates were also applied to III, but all failed to produce I. Chlorination of either I or III gave an acyclic product, 4, 4-bis(chloromethyl)-1, 1, 7, 7-tetrachloro-2, 6-dioxa-1, 7-di-phosphaheptane-1, 7-dioxide (IV), in nearly quantitative yield. The same compound was also obtained by the previously known method of chlorinating 3, 9-dichloro-2,4,8,10-tetraoxa-3, 9-diphosphaspiro[5.5]undecane (II). The treatment of pentaerythritol with phosphorus pentachloride gave IV in minor amount along with a 25% yield of 4,4-bis-(chloromethyl)-1-chloro-2, 6-dioxa-1-phosphacyclohexane-1-oxide (VII). The hydrolysis of I in heated aqueous sodium carbonate gave, after acidification, 3,9-dihydroxy-2,4,8,10-tetraoxa-3, 9-diphosphaspiro[5. 5]undecane-3, 9-disulfide (VIII). A number of derivatives were prepared by reaction of I with phenoxides and amines. The corresponding thio-phosphorofluoridate XI was prepared by treatment of I with potassium fluoride in dioxane.     

Application of the Weisz Ring oven technique to the separation and identification of micro-quantities of some less familiar cations

Summary Use of the ring oven in separation and identification of mixtures of less familiar metal ions has been described. Separation of metal ions from the following mixtures has successfully been carried out: 1. UO₂(II) and Th(IV), 2. Th(IV) and Ce(IV), 3. Pd(II) and Au(III), 4. Pt(IV) and Au(III), 5. Ce(III) and Ce(IV), 6. UO₂(II), Th(IV) and Ti(IV), 7. Th(IV), Ti(IV) and Ce(IV), 8. Th(IV), Ce(IV) and Zr(IV), 9. Ti(IV), V(V) and Zr(IV), 10. Mo(VI), V(V) and W(VI) and 11. Be(II), Al(III) and Mg(II). In the case of binary mixtures, the separation was in the form of a central spot and a concentric ring; in ternary mixtures the metals were precipitated in a central spot and two concentric rings.

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Zusammenfassung Zur Trennung und Identifizierung folgender Gemische seltenerer Metallionen wurde der Ringofen mit Erfolg verwendet: 1. UO₂(II) und Th(IV), 2. Th(IV) und Ce(IV), 3. Pd(II) und Au(III), 4. Pt(IV) und Au(III), 5. Ce(III) und Ce(IV), 6. UO₂(II), Th(IV) und Ti(IV), 7. Th(IV), Ti(IV) und Ce(IV). 8. Th(IV), Ce(IV) und Zr(IV), 9. Ti(IV), V(V) und Zr(IV), 10. Mo(VI), V(V) und W(VI) und 11. Be(II), Al(III) und Mg(II). Bei binären Gemischen erfolgt die Trennung in einen zentralen Fleck und einen Ring, bei ternären Mischungen in einen Fleck und zwei konzentrische Ringe.

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Résumé On a décrit l'utilisation du four annulaire pour la séparation et l'identification de mélanges d'ions métalliques moins courants. On a effectué la séparation des ions métalliques à partir des mélanges suivants: 1. UO₂(II) et Th(IV), 2. Th(IV) et Ce(IV), 3. Pd(II) et Au(III), 4. Pt(IV) et Au(III), 5. Ce(III) et Ce(IV), 6. UO₂(II), Th(IV) et Ti(IV), 7. Th(IV), Ti(IV) et Ce(IV), 8. Th(IV), Ce(IV) et Zr(IV), 9. Ti(IV), V(V) et Zr(IV), 10. Mo(VI), V(V) et W(VI) et 11. Be(II), Al(III) et Mg(II). Dans le cas des mélanges binaires, la séparation se présentait sous forme d'une tache centrale et d'un anneau concentrique; chez les mélanges ternaires, les métaux étaient précipités en une tache centrale et deux anneaux concentriques.

     

17α-羟基-16β-甲基-5,9(11)-孕甾二烯-3,20-二缩酮的D环高碳化

报导了17α-羟基-16β-甲基-4,9(11)孕甾二烯-3,20-二缩酮(1)用70%醋酸进行的水解反应. 结果得相应的3,20-二酮化合物(2). 当用98%醋酸处理(1)不能获得(2). 而是重排成17α-羟基-16β, 17β-二甲基-D-高孕甾二烯二酮(3). 当化合物(1)和(2)与含有CaCl2的70%醋酸反应获得16β, 17β-二甲-D-高-4,9(11), 15-孕甾三烯-3,17-二酮, 其得率取决于CaCl2的浓度和反应时间.     

Molybdenum and copper catalysis of reductions by titanium(II) and titanium(III)

Reductions of vanadium(IV), benzoquinone, and tri-iodide, both by titanium(III) and by titanium(II), are catalyzed by molybdenum(VI). The VO(2+)-Ti(II) reaction is catalyzed by copper(II) as well. Reactions of Ti(II) with the oxidant in excess yield Ti(IV), as do reductions by Ti(III). Reactions proceed via competing uncatalyzed and catalyzed paths, with the latter components first order in catalyst. Kinetic patterns indicate that monomeric Mo(v) is the active species, but the dimeric Mo(v) species, [Mo(2)O(4)](2+), is without catalytic action. Catalytic constants pertaining to Ti(III) are remarkably similar to those for Ti(II), despite the 0.47 V difference in the standard potentials of the two reductants.     

Oximidobenzotetronic acid as a reagent for the separation and gravimetric determination of palladium and cobalt

Oximidobenzotetronic acid is recommended for the separation and gravimetric determination of palladium and cobalt An ethanolic solution of the reagent quantitatively precipitates palladium(II) from solutions which are 0.75 N in acid up to pH 5.1, the complex is weighed as Pd(C₉H₅NO₄)₂. Cobalt(II) can be determined in the filtrate after the precipitation of palladium. With 0.5 N acid solutions, no interference was found from Pt(IV), Ir(IV), Rh(III), Ru(III), Os(IV), Au(III), Ag(I), Cu(II), Fe(III), Ni(II), Hg(II). Pb(II), Bi(III), Cd(II), As(V), Se(VI), Te(IV), Mo(VI), Sb(III), Al(III), Cr(III), Zn(II), Ti(IV), Zr(IV). acetate, oxalate, citrate, tartrate, phosphate and fluoride.     

Synthetic and computational studies of the palladium(iv) system Pd(alkyl)(aryl)(alkynyl)(bidentate)(triflate) exhibiting selectivity in C-C reductive elimination

Synthetic routes to methyl(aryl)alkynylpalladium(iv) motifs are presented, together with studies of selectivity in carbon-carbon coupling by reductive elimination from Pd(IV) centres. The iodonium reagents IPh(C[triple bond, length as m-dash]CR)(OTf) (R = SiMe(3), Bu(t), OTf = O(3)SCF(3)) oxidise Pd(II)Me(p-Tol)(L(2)) (1-3) [L(2) = 1,2-bis(dimethylphosphino)ethane (dmpe) (1), 2,2'-bipyridine (bpy) (2), 1,10-phenanthroline (phen) (3)] in acetone-d(6) or toluene-d(9) at -80 °C to form complexes Pd(IV)(OTf)Me(p-Tol)(C[triple bond, length as m-dash]CR)(L(2)) [R = SiMe(3), L(2) = dmpe (4), bpy (5), phen (6); R = Bu(t), L(2) = dmpe (7), bpy (8), phen (9)] which reductively eliminate predominantly (>90%) p-Tol-C[triple bond, length as m-dash]CR above ～-50 °C. NMR spectra show that isomeric mixtures are present for the Pd(IV) complexes: three for dmpe complexes (4, 7), and two for bpy and phen complexes (5, 6, 8, 9), with reversible reduction in the number of isomers to two occurring between -80 °C and -60 °C observed for the dmpe complex 4 in toluene-d(8). Kinetic data for reductive elimination from Pd(IV)(OTf)Me(p-Tol)(C[triple bond, length as m-dash]CSiMe(3))(dmpe) (4) yield similar activation parameters in acetone-d(6) (66 ± 2 kJ mol(-1), ΔH(?) 64 ± 2 kJ mol(-1), ΔS(?)-67 ± 2 J K(-1) mol(-1)) and toluene-d(8) (E(a) 68 ± 3 kJ mol(-1), ΔH(?) 66 ± 3 kJ mol(-1), ΔS(?)-74 ± 3 J K(-1) mol(-1)). The reaction rate in acetone-d(6) is unaffected by addition of sodium triflate, indicative of reductive elimination without prior dissociation of triflate. DFT computational studies at the B97-D level show that the energy difference between the three isomers of 4 is small (12.6 kJ mol(-1)), and is similar to the energy difference encompassing the six potential transition state structures from these isomers leading to three feasible C-C coupling products (13.0 kJ mol(-1)). The calculations are supportive of reductive elimination occurring directly from two of the three NMR observed isomers of 4, involving lower activation energies to form p-TolC[triple bond, length as m-dash]CSiMe(3) and earlier transition states than for other products, and involving coupling of carbon atoms with higher s character of σ-bonds (sp(2) for p-Tol, sp for C[triple bond, length as m-dash]C-SiMe(3)) to form the product with the strongest C-C bond energy of the potential coupling products. Reductive elimination occurs predominantly from the isomer with Me(3)SiC[triple bond, length as m-dash]C trans to OTf. Crystal structure analyses are presented for Pd(II)Me(p-Tol)(dmpe) (1), Pd(II)Me(p-Tol)(bpy) (2), and the acetonyl complex Pd(II)Me(CH(2)COMe)(bpy) (11).     

Reductions by titanium(II) as catalyzed by titanium(IV)

The cobalt(III) complexes, [(NH3)5CoBr]2+ and [(NH3)5CoI]2+ are reduced by Ti(II) solutions containing Ti(IV), generating nearly linear (zero-order) profiles that become curved only during the last few percent of reaction. Other Co(III)-Ti(II) systems exhibit the usual exponential traces with rates proportional to [Co(III)]. Observed kinetics of the biphasic catalyzed Ti(II)-Co(III)Br and Ti(II)-Co(III)I reactions support the reaction sequence: [Ti(II)(H20)n]2+ + [Ti(IV)F5]- (k1)<==>(k -1) [Ti(II)(H2O)(n-1)]2+ + [(H2O)Ti(IV)F5]-, [Ti(II)(H2O)(n-1)]2+ + Co(III) (k2)--> Ti(III) + Co(II) with rates determined mainly by the slow Ti(IV)-Ti(II) ligand exchange (k1 = 9 x 10(-3) M(-1) s(-1) at 22 degrees C). Computer simulations of the catalyzed Ti(II)-Co(III) reaction in perchlorate-triflate media yield relative rates for reduction by the proposed active [Ti(II)(H2O)(n-1)]2+ intermediate; k(Br)/k(I) = 8.     

Synteesis of 2-Adamantane Carboxylic Acid

Despite the fact that there are two well-described routes to 2-adamantane carboxylic acid (IV)^1,2 it is not an easily accessible compound. In connection with our work in the field of adamantane ketenes and other 2-substituted adamantane derivatives^5,6 on adamantanone (I), followed by conversion of the enol ether (II) to the aldehyde (III) and oxidation of the latter to give 2-adanabtabe carvixtkuc acud (IV). The yield of this one-pot procedure is 70%-75% (about 10 runs).     

Synthesis of Polyacrylaminothiourea Chelating Fiber and Properties of Concentration and Separation of Trace Noble Metal Ions from Samples

A novel polyacrylaminothiourea chelating fiber was synthesized simply and rapidly from nitrilon (an acrylonitrile-based synthetic fiber), which was applied to preconcentrate and separate of trace amount of Au(Ⅲ）,Pt(Ⅳ）,Pd(Ⅳ） and Ir (Ⅳ） ions from solution of samples.The analyzed ions can be quantitatively concentrated by the fiber up to a flow rate of 20.0mL/min at pH2, and can also be desorbed with 15 mL of 4mol/L HCl 3% thiourea from the fiber column with recoveries of 96.5%-100%.The chelating fiber can be reused for ten times,the recoveries of these ions are still over 92%,and hundred to thousand times of excess of Fe(Ⅲ）,Al（Ⅲ）,Ca(Ⅱ），Mg（Ⅱ）,Ni(Ⅱ）,Mn（Ⅱ),Cu(Ⅱ），Zn(Ⅱ），and Cd(Ⅱ） cause no interference on the determination of the analyzed ions by inductively-coupled plasma atomic emission spectrometry (ICP-AES).The static saturation adsorption capacities of the fiber for the analytes are in the range of 1.15-2.80mmol/g.The relative standard deviations for the determination of 20.0ng/mL each of Au(Ⅲ）,Pt(Ⅳ）,Pd(Ⅳ）and Ir(Ⅳ） are in the range of 0.7%-3.0%.The recoveries for test from standard additions to real solution samples are between 96% and 100%.The concentration of each ion in powder sample detected by the method is in good agreement with the certified value.     

Reductions of oxo species by aquatitanium(II) as catalyzed by titanium(IV)

Titanium(II) solutions, prepared by dissolving titanium wire in triflic acid + HF, contain equimolar quantities of Ti(IV). These preparations react readily with oxidizing species such as VO(2)(+), substituted benzoquinones, and the biguanide complex of Mn(IV). Reactions with excess Ti(II) yield Ti(III). Reductions of 1,4-benzoquinones and the Mn(IV) complex are catalyzed by added Ti(IV) but stoichiometry is unaffected. Rate laws for the Ti(IV)-catalyzed reactions are consistent with formation of a Ti(II)-Ti(IV) complex (K(formation) 4 x 10(2) M(-1)), which, in some cases, also partakes in contributing deprotonated and halogen-catalyzed paths.     

Copper(II) complexation and extraction with 2-ethylhexanoic acid <Emphasis Type="Italic">N</Emphasis>′,<Emphasis Type="Italic">N</Emphasis>′-dialkylhydrazides

2-Ethylhexanoic acid N′,N′-dibutylhydrazide (DBH) and N′,N′-diheptylhydrazide (DHH) were synthesized. The existence regions of copper (II), zinc(II), nickel(II), and cobalt(II) complexes formed upon extraction with DBH in kerosene were studied. The neutral complex ML₂ extracted over a wide pH range (from pH ～ 6 to \(c_{NH_3 } \) ～ 4 mol/L) is formed only by copper(II), while zinc(II), nickel(II), and cobalt(II) react with DBH to yield precipitates that float at pH 7–9, 9–10.5, and 9.5–11, respectively. On the basis of IR spectra, elemental analysis, and properties, a structure was suggested for the CuL₂ complex with DBH. The DBH and DHH complexes with copper(II) are readily stripped with H₂SO₄ and H₂SO₄ + CuSO₄ solutions. The capacity of a 1.5 mol/L DHH in kerosene with respect to copper(II) is 26 g/L.     

Studies on the syntheses of analgesics. Part XXXII. An alternative synthesis of 1,2,3,4,5,6-Hexahydro-8-hydroxy-6,11-dimethyl-3-(3-methyl-2-butenyl)-2,6-methano-3-benzazoeine [Studies on the syntheses of heterocyclic compounds. Part CDLXXX]

Bischler-Napieralski reaction of the amides (VIII and IX), derived from the 3-methyl-3-pentenylamine (III) with the phenylacetic acid derivatives (V ～ VII), gave the 5,6-dihydropyridines (XII and XIII), which were reduced, followed by N-benzylation, to afford the 1,2,5,6-tetrahydropyridines (XIX ～ XXI). Grewe-type cyclization of these compounds gave 3-benzyl-3-benzazocine (II), which was already converted into pentazocine (Ic). Moreover, the 1,2,5,6-tetrahydropyridines (XIX ～ XXI) were also obtained from the 2-benzylidene-1,2,5,6-tetrahydropyridine (XVII ～ XVIII) from the N-benzylamine (IV) of III via the amides (X and XI).     

Solvent Extraction Separation of Germanium(IV) with N-<Emphasis Type="Italic">n</Emphasis>-Octylaniline As an Extractant

The extraction behavior of germanium(IV) from aqueous hydrochloric acid solution with N-n-octylaniline in xylene was investigated. Hydrochloric acid concentration higher than 9 M remained effective for quantitative extraction of germanium(IV). Phenylfluorone ion as a counter anion was used. More than 2% N-n-octylaniline provided quantitative extraction at 1 min equilibrium time and germanium(IV) was back extracted by 7 M ammonia. The method was free from the interference of a large number of metal ions and anions, except for Te(IV) and Sn(IV); this was avoided using the masking effect. Germanium(IV) was separated from associated elements in its binary mixture with Si(IV), Te(IV), Sb(III), Bi(III), Au(III), Cu(II), Zn(II), and its ternary mixture with Se(IV), Te(IV); Sb(III), Bi(III); and Au(III), Cu(II). The proposed method was applied to a synthetic sample containing associated metal ions. The results indicated that trace amounts of germanium(IV) could be separated effectively from higher amounts of other elements.__________From Zhurnal Analiticheskoi Khimii, Vol. 60, No. 5, 2005, pp. 463–467.Original English Text Copyright © 2005 by Sargar, Anuse.This article was submitted by the authors in English.     

Synthesis and Efficiency of an Epoxy-Urea Chelating Resin for Preconcentrating and Separating Trace Bi,In, Sn,Zr, V And Ti From Solution Samples

Abstract

A new epoxy-urea chelating resin was synthesized from epoxy resin and used for the preconcentration and separation of trace Bi(III), In(III), Sn(IV), Zr(IV), V(V) and Ti(IV) ions from solution samples. The analyzed ions can be enriched at pH 5 at a flow rate of 1–4 ml/min, and can be also desorbed with 10 mL of 2 M HCl +0.1g NH₄F solution from the resin column, with recoveries over 97%. The chelating resin reused 6 times can still adsorb quantitatively the Bi, In, Sn, Zr, V and Ti ions, and eighty to thousand-fold excesses of Ca(II), Mg(II), Cu(II), Zn(II), Al(III), Sb(III), Ni(II), Mn(II) and Fe(III) cause little interference with the enrichment and determination of these ions. The RSDs of the proposed method for the determination of 500–50 ng/ml Bi, In and Sn, 50–5.0 ng/ml Zr, V and Ti were in the range of 0.4 ～ 4.0%, the enrichment factor of the resin for the ions is in the range of 10–100. The recoveries of added standard in waste water are between 96% and 100%, and the concentration of each ion in alloy steel sample determined by the method is in good agreement with the reference value analyzed by a steel plant with average error <2.8%.     

Analytical characterization of a silica gel sorbent with thioetheric sites

The sorption behavior of a newly synthesized silica gel sorbent with thioetheric sites (STS) towards microgram levels of Au(III), Pt(IV) and Pd(II) was studied. Au(III) is quantitatively (>95%) sorbed in the pH region of 1–9. The sorption of Pt(IV) starts at pH 1 and does not exceed 25% in the entire pH region examined. The sorption of Pd(II) starts at pH 7 and reaches 80% at pH 9. The sorption of Au(III) on STS at pH 1 is not affected by milligram amounts of Ni(II), Zn(II), Fe(III), Cu(II), Pb(II), Cd(II) or Co(II). Au(III) is quantitatively eluted with a 5% aqueous solution of thiourea. The adsorption capacity of STS towards Au(III) is 195 mg g⁻¹. The detection limit (DL) of Au(III) (3σ, n = 9) is 25 ng mL⁻¹. The RSD at a level of 10 × DL is about 2%. Solid-phase extraction of trace amounts of Au(III) on the STS sorbent, followed by its flame AAS determination in the eluate was applied to the determination of gold in geological samples. The results obtained for the gold content in the samples were in good agreement with those of the ICP-AES analysis.     

选择性反应及其合成应用的研究--Ⅰ.高度区域及立体选择性硼氢化和1,2:5,6一二一(0-亚异丙基)-α-D-半乳-呋喃糖合成方法的改进

由D—葡萄糖(Ⅰ),经四步反应可得标题化合物(Ⅴ)。为了在较短的时间内制得足够量的纯净的3—脱氧1,2:5,6—二(O—亚异丙基)—α—D—赤—己—3—烯呋喃糖(Ⅳ),可将3—O—对甲苯磺酰基—1,2:5,6—二—(O—亚异丙基)—α—D—葡—呋喃糖(Ⅲ)和粉状氢氧化钾置于Kugelrohr装置中进行反应。仔细控制反应条件,化合物(Ⅳ)的产率达到72％。在硼烷—甲硫醚配合物(H_3B:SMe_2)与烯(Ⅳ)起硼氢化反应后,用碱性过氧化氢处理,可得产物(Ⅴ),产率76—81％。此硼氢化反应具有高度区域选择性和立体选择性。     

四(4,4',4'',4'''-N,N-二氨基)四苯乙烯光致发光与分子的构象效应

利用还原偶联方法合成出新化合物四(4,4',4',4''-N,N-二氨基)四苯乙烯（ TDETE）。通过测定该化合物在溶液、掺杂聚合物中及晶体粉末的稳态-瞬态荧光光 谱、荧光量子产率和辐射衰变速率常数等。讨论了分子的构象效应等因素对TDETE 光致发光行为的影响。在一定浓度下TDETE溶液存在着三个发光带,分别为全扭曲 构象分子（位于345nm附近的发光I带）、半扭曲构象分子（位于430nm附近的发光 II带）和激基缔合物（530发光III带）的辐射衰变所致。在聚合物（PMMA）中,一 方面由于分子单键的自由旋转扭曲受到遏制,表现为II带的辐射衰变速率常数(kf 值)增大、同时非辐射衰变速率常数knf值减小;另一方面,TDETE分子之间相互作 用得到加强而有利一缔合物形成,结果,使发光II带和III带合二为一出现强而宽 的发射峰,荧光量子产率从溶液中的0.055提高到0.855。此外,在PMM介制裁中观 测到TDETE分子聚集体在626nm处的发光带（IV）,数粉末态中聚集体IV带的强度骤 增,峰值波长红移至650nm。