PYRROMETHENE-BF2 COMPLEXES AS LASER-DYES .2.
PYRROMETHENE-BF2 COMPLEXES AS LASER-DYES .2.
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DOI：
10.1002/hc.520040107
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发表时间：
1993-02-01
影响因子：
0.3
通讯作者：
PAVLOPOULOS, TG
中科院分区：
文献类型：
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作者：
BOYER, JH;HAAG, AM;PAVLOPOULOS, TG
以α-未取代吡咯5为原料，经酰化、缩合反应制得中间体吡咯亚甲基氢卤化物6，再与三氟化硼进行醚化反应，制得吡咯亚甲基-BF2络合物(P-BF2)7。将α-吡咯甲酸乙酯4转化为α-未取代吡咯5是通过在160℃的磷酸中进行热分解，或者通过皂化然后在180℃的乙醇胺中脱羧基来实现的，或者通过在甲酸和氢溴酸的混合物中加热作为未分离的中间产物将酯4转化为氢溴化吡咯亚胺6。加入氰化氢，然后用溴处理脱氢，将3，5，3‘，5’-tetramethyl-4，4‘-diethylpyrromethene氢溴酸盐9转化为3，5，-3’，5‘-tetramethyl-4，4’-diethyl-6-cyanopyrromethene氢溴酸盐6BB，在用三氟化硼醚处理时进一步转化为1，3，5，7-tetra-methyl-2，6-diethyl-8-cyanopyrromethene-BF2络合物7BB。1，3，5，7，8-pentamethyl-2，6-di-n-alkylpyrromethene-BF2染料中激光活性的相对效率(PE)的交替效应取决于正烷基取代基中的亚甲基单元的数量，-(CH2)NH，当n=0，2，4时，PE等于或大于100，当n=1，3时，PE=65，85。(PE 100被任意分配给染料罗丹明6G)。1，3，5，7-tetramethyl-2，6-diethyl-8-isopropylpyrromethene-BF2络合物7P没有荧光和激光活性，1，3，5，7-tetramethyl-2，6-diethyl-8-cyclohexylpyrromethene-BF2络合物7q的荧光量子产率(PHI0.23)和激光活性明显降低，这归因于两个体积较大的8-取代基与1，7-二甲基取代基之间的空间干涉所导致的分子非平面性。对于没有空间位阻干扰的过烷基化染料，观察到1，2，6，7-bistrimethylene-3，5，8-trimethylpyrromethene-BF2络合物7J的反常低的RE20。通过与全烷基化染料的比较，发现6种染料7U-z缺少8位取代，RE0-40显著降低，2，6-二苯基衍生物71，RE20和1，3，5，7，8-五甲基吡咯亚甲基-BF2络合物(PMP-BF2)7a和1，7-dimethoxy-2，3，5，6，8-pentamethylpyrromethene-BF2络合物7n，RE30的官能团(极性)取代导致了较低的激光活性。二乙基1，3，5，7-tetramethyl-8-cyanopyrromethene-2，6-dicarboxylate-BF2络合物7AA和1，3，5，7-tetramethyl-2，6-diethyl-8-cyanopyrromethene-BF，络合物7BB提供了在8位带有吸电子取代基的P-BF_2染料的例子。染料7AA，Lambda(LAS)617 nm，显示出近两倍于罗丹明B，Lambda(LAS)611 nm的功率效率。
Pyrromethene-BF2 complexes (P-BF2) 7 were obtained from alpha-unsubstituted pyrroles 5 by acylation and condensation to give intermediate pyrromethene hydrohalides 6 followed by treatment with boron trifluoride etherate. Conversion of ethyl alpha-pyrrolecarboxylates 4 to alpha-unsubstituted pyrroles 5 was brought about by thermolysis in phosphoric acid at 160-degrees-C, or by saponification followed by decarboxylation in ethanolamine at 180-degrees-C, or as unisolated intermediates in the conversion of esters 4 to pyrromethene hydrobromides 6 by heating in a mixture of formic and hydrobromic acids. Addition of hydrogen cyanide followed by dehydrogenation by treatment with bromine converted 3,5,3',5'-tetramethyl-4,4'-diethylpyrromethene hydrobromide 9 to 3,5,-3',5'-tetramethyl-4,4'-diethyl-6-cyanopyrromethene hydrobromide 6bb, confirmed by the further conversion to 1,3,5,7-tetra-methyl-2,6-diethyl-8-cyanopyrromethene-BF2 complex 7bb on treatment with boron trifluoride etherate.An alternation effect in the relative efficiency (PE) of laser activity in 1,3,5,7,8-pentamethyl-2,6-di-n-alkylpyrromethene-BF2 dyes depended on the number of methylene units in the n-alkyl substituent, -(CH2)nH, to give PE equal-to-or-greater-than 100 when n = 0,2,4 and RE 65, 85 when n = 1,3. (The PE 100 was arbitrarily assigned to the dye rhodamine 6G). The absence of fluorescence and laser activity in 1,3,5,7-tetramethyl-2,6-diethyl-8-isopropylpyrromethene-BF2 complex 7p and a markedly diminished fluorescence quantum yield (PHI 0.23) and lack of laser activity in 1,3,5,7-tetramethyl-2,6-diethyl-8-cyclohexylpyrromethene-BF2 complex 7q were attributed to molecular nonplanarity brought about by the steric interference between each of the two bulky 8-substituents with the 1,7-dimethyl substituents. An atypically low RE 20 for a peralkylated dye without steric interference was observed for 1,2,6,7-bistrimethylene-3,5,8-trimethylpyrromethene-BF2 complex 7j. Comparisons with peralkylated dyes revealed a major reduction in RE 0-40 for the six dyes 7u-z lacking substitution at the 8-position.Low laser activity RE was brought about by functional group (polar) substitution in the 2,6-diphenyl derivative 71, RE 20, and the 2,6-diacetamido derivative 7m, RE 5, of 1,3,5,7,8-pentamethylpyrromethene-BF2 complex (PMP-BF2) 7a and in 1,7-dimethoxy-2,3,5,6,8-pentamethylpyrromethene-BF2 complex 7n, RE 30. Diethyl 1,3,5,7-tetramethyl-8-cyanopyrromethene-2,6-dicarboxylate-BF2 complex, 7aa, and 1,3,5,7-tetramethyl-2,6-diethyl-8-cyanopyrromethene-BF, complex, 7bb, offered examples of P-BF2 dyes with electron withdrawing substituents at the 8-position. The dye 7aa, lambda(las) 617 nm, showed nearly twice the power efficiency that was obtained from rhodamine B, lambda(las) 611 nm.