The photophysical properties of two new tetra substituted derivatives of pyrene: 1,3,6,8-tetraethynylpyrene (TEP) and 1,3,6,8-tetrakis(trimethylsilylethynyl)pyrene (TEP-TMS) have been studied. Studies were done with respect to mirror image symmetry in the absorption and emission spectra and permissive or forbidden nature of S₀–S₁ transition, solvent sensitivity of the first and third vibronic bands and fluorescence anisotropy. Both the derivatives exhibited a strongly allowed S₀–S₁ transition, high fluorescence quantum yield, shorter fluorescence lifetime compared to pyrene and invariance of the vibronic band intensity ratio to solvent polarity. The behavior of the two pyrene derivatives validates the hypothesis “solvent polarity mediates vibronic coupling and therefore the emission band intensities, for forbidden S₀–S₁ transitions”. The trimethylsilyl derivative (TEP-TMS) was characterized by a strong fluorescence in solid state. The tetraethynyl derivative (TEP) showed high fluorescence anisotropy comparable to the well-known anisotropy probe DPH in glycerol at 0 °C. The fluorescence intensities of TEP and TEP-TMS did not show any significant change in the temperature ranger 0–40 °C for a low viscous solvent like ethanol and in the range 0–60 °C in glycerol. Unlike pyrene, no excimer emission was observed even up to 10⁻³ M for TEP and TEP-TMS.

中文翻译：

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1,3,6,8-四乙炔基py和1,3,6,8-四（三甲基甲硅烷基乙炔基）pyr：在均相介质中的光物理性质

研究了两种新的tetra的四取代衍生物的光物理性质：1,3,6,8-四乙炔基py（TEP）和1,3,6,8-四（三甲基甲硅烷基乙炔基）py（TEP-TMS）。关于吸收和发射光谱中的镜像对称性以及S ₀ -S ₁跃迁的允许或禁止性质，第一和第三振动带的溶剂敏感性以及荧光各向异性，进行了研究。两种导数均显示出强烈允许的S ₀ –S ₁相变，与quantum相比，荧光量子产率高，荧光寿命短，以及电子束带强度比与溶剂极性的不变性。两种pyr衍生物的行为验证了以下假设：“对于禁止的S ₀ –S ₁，溶剂的极性介导了振动耦合，因此发射带强度。过渡”。三甲基甲硅烷基衍生物（TEP-TMS）的特点是固态荧光强。四乙炔基衍生物（TEP）在0°C的甘油中显示出与众所周知的各向异性探针DPH相当的高荧光各向异性。对于低粘度溶剂（如乙醇），TEP和TEP-TMS的荧光强度在0–40°C的温度范围内以及甘油在0–60°C的范围内均未显示任何显着变化。不像芘，没有受激准分子发光观察甚至高达10 ^-3  M代表TEP和TEP-TMS。