The photochemical reaction of 4-nitroindole and guanosine was studied with the transient absorption spectroscopy as guanine is an effective hole trap during the charge transfer in DNA, and 4-nitroindole is a universal base. Excitation of 4-nitroindole generates the lowest triplet excited state 4-nitroindole (³HN-NO₂) within 10 ns in the quantum yield 0.41. ³HN-NO₂ has increased basicity compared to its ground state. Consequently, its nitro group exhibits the hydrogen bond accepting ability. ³HN-NO₂ can interact with guanosine (G) to form the hydrogen-bonded ³HN-NO₂^…G complex with the rate constant k=(8.7 ± 0.3)×10⁹ M⁻¹⋅s⁻¹. The hydrogen-bonded complex is identified based on the blue shift evolvement of the absorption maximum of ³HN-NO₂ in alcoholic solutions. The reduction potential of ³HN-NO₂ is E_red(³HN-NO₂) = 1.23 V vs. SCE. The electron transfer occurs in the ³HN-NO₂^…G complex and generates G^+• and HN-NO₂−• followed by the proton transfer from N₁ and N₂ of G producing radicals HN-NO₂H^•, G(N₁-H)^• and G(N₂-H)^•.

用鸟嘌呤是DNA电荷转移过程中的有效空穴陷阱，而4-硝基吲哚是通用碱，因此采用瞬态吸收光谱法研究了4-硝基吲哚和鸟嘌呤的光化学反应。4-硝基吲哚的激发在10 ns内产生最低的三重态激发态4-硝基吲哚（³ HN-NO ₂），量子产率为0.41。³ HN-NO ₂与基态相比增加了碱度。因此，其硝基具有氢键接受能力。³ HN-NO ₂可以与鸟嘌呤（G）相互作用形成氢键结合的³ HN-NO ₂ ^… G络合物，速率常数k =（8.7±0.3）×10^9个中号^-1 ⋅s ^-1。基于酒精溶液中³ HN-NO _2的最大吸收量的蓝移演变，确定了氢键配合物。³ HN-NO ₂的还原电位为E _red（³ HN-NO ₂）= 1.23 V vs. SCE。电子转移发生在³ HN-NO ₂ ^… G络合物中，并生成G ^+•和HN-NO _2- •，然后从G的N ₁和N ₂进行质子转移，产生自由基HN-NO ₂ H ^•，G（N ₁ -H）^•和G（N ₂ -H）^•。