Structure,biological Activity And Structure-Activity Relationship Of Transition Metal Complexes With Uniconazole And Paclobutrazol

With the development of modern agriculture,some crop-threatening pathogenic fungi cause large decreases in crop yields.1,2,4-Triazole fungicides own the adv antages of low tox icity,high efficiency,and systemic transmission.However,the abuse of this kinds of fungicides has resulted in a rapid selection and large dosage usage,which has caused certain pollution.Thus,there are urgent needs for studies on new,efficient and ecofriendly fungicides.Nowdays,many chemists show that the coordination with effective fungicides and metal salts is an effective way to obtain more novel complexes.In addition,these complexes have underlying advantages of the enhanced biological active ities,friendliness,and low tox icity.By the way,compared to the development of new drugs in organic synthesis,adopting coordination to synthesis novel fungicides is a simple and feasible method,which could improve the mechanism of ligand itself,and joined the metals needed for the crops.Synergistic action not only improves the efficacy but also solves the problem of drug resistance.Therefore,this paper conducts an in-depth study on metal complexes.It is well known that N atom of the Triazole ring plays a key role in the coordination of metals at the active sites of many metallo-biomolecules.The importance of metal ions playing in biological activity is well established.One of the most attractive characteristic of metal-coordinated systems is the coordinated arrangement of the ligands around the metal salt.Besides,the fungicides complexes can be served as sustained release formulations.They could extend the effecacy and decrease fungicide dosage.Now,the widely used fungicides uniconazole L¹ and paclobutrazol L² have been used as ligands to synthesize16 complexes.And crystal structures the biological activity and structure-activity relationship have been researched in the the microscopic view to sort out better biological complex fungieides.Firstly,16 novel metal complexes with uniconazole L¹ and paclobutrazol L² were synthesized and their crystal structures are detected by XRD.There are eleven complexes with uniconazole L¹:[CuL₄¹?H₂O?₂]?2?NO₃??4EtOH?1?,[CuL₂¹?CH₃COO?₂?EtOH?₂]?2?,[CuL₄¹Br₂]?3?,[ZnL₂¹?SO₄?]_n?4?,[ZnL₄¹?H₂O?₂]?2?NO₃??4EtOH?5?,[ZnL₂¹Cl₂]?L¹?6?,[ZnL₂¹Br₂]?L¹?7?,[CoL₄¹?H₂O?₂]?2?NO₃??4EtOH?8?,[CoL₂¹?CH₃COO?₂?MeOH?₂]?9?,[NiL₄¹?H₂O?₂]?2?NO₃??4EtOH?10?,[NiL₂¹?CH₃COO?₂?EtOH?₂]?11?.There are five complexes based on paclobutrazol L².Among them,[CuL₄²?NO₃?₂]?2EtOH?2?H₂O??12?,[ZnL₄²?NO₃?₂]·2EtOH·2H₂O?13?,[CoL₄²?NO₃?₂]·2EtOH·2H₂O?14?,[Co L₂²?CH₃COO?₂?EtOH?₂]?15?,[CoL₄²Cl₂]?16?.Secondly,the antifungal activi ties of the complexes were studied.The antifungal activities against the four fungi[Botryosphaeria ribis?I?,Botryosphaeria berengriana?II?,Wheat.gibberellic?III?,Grape.Anthracnose?IV?]were measured by EC₅₀values.It is found that all the complexes agaist the fungi are better than the corresponding ligands.And the complexes of[ZnL₂¹?SO₄?]_n and[CuL₂¹?CH₃COO?₂?EtOH?₂]have better antifungal activity than other complexes against the four fungi.Among them,the whole metal complexes have a good antifungal activity against Botryosphaeria ribis?I?,and the EC₅₀is within the range of 0.087-0.878mg/L.For the sake of eluciding the increase degree of the antifungal activity of the complexes compared with their parent ligands,the synergistic coefficient?SR value?is used.The complexes can be supposed as the mole cular-level mix tures.And the SR values of[ZnL₂¹?SO₄?]_n and[CuL₂¹?CH₃COO?₂?EtOH?₂]against Botryosphaeria ribis?I?are reached18.58 and 16.45,respectively.The synergistic effect of the acetate metal complexes with the same metal cation was higher than that of the nitrate metal complexes.The synergistic effect of four nitrate metal complexes is in the order of[CuL₄¹?H₂O?₂]?2?NO₃??4EtOH>[ZnL₄¹?H₂O?₂]?2?NO₃??4EtOH>[CoL₄¹?H₂O?₂]?2?NO₃??4EtOH>[Ni L₄¹?H₂O?₂]?2?NO₃??4EtOH for the same tested fungi.The Cu?II?and Zn?II?complexes have the higher synergistic leval than other complexes.It has been found that the com p lexes have better biological acti vities than the corresponding ligands ascribed to the synerg istic interaction.In addition,the plant growth regulating effect of the 16 obtained complexes were studied,it is found that plant growth regulating effect of metal complexes were superior to the corresponding ligands.Compared with other metal complexes,the effect of Zn?II?complexes on plant height inhibition and root shoot ratio in wheat was obvious.It is shown that zinc complexes have better plant growth regulating effect than other complexes due to the synergistic interaction between ligand and metal salt.Finally,frequency simulation,frontier orbitals distribution,and Mulliken charges analysis were studied by DMol³.It speculates that there could be two causes for the enhanced activity:For one hand,there add the active sites of metal cation and anion;For another hand,in the process of complexation,there is the transferred charge,which is ascribed to the depressed polarity of the complexes and the enhanced penetration of complexes.