The only use I know of for baking soda is to control powdery mildew. The pictures are not clear enough to see if that's what the plants have but powdery mildew does not cause the kind of wilting that we can see.
This plant is the night blooming jasmine or Cestrum nocturnum, a flowering shrub native to the west Indies but now naturalized in Asia, South Africa, New Zealand and commonly found in North America where the temperatures remain above 10 deg C ( 15 deg F).
The wilt could be a fungus/virus/bacteria causing root rot or the plant could be under watered.
Consider these suggestions:
- when you water add enough water that it runs out of the drain holes in the pot. If you do not have drain holes in the pot that could be your problem. After watering let the top ten percent of the soil dry out before watering again.
- consider removing all the wilted leaves and any dead leaves on top of the soil. They will not un wilt so you might as well act.
- ensure the plant is located so it received bright sunlight for at least eight hours a day
- the tough love approach would be to cut the plant back at least two thirds to a strong stem. Reduce watering and wait and see