In this paper, we consider the complex Ginzburg--Landau equation ut=eiθ[Δu+∣u∣αu]+γu on RN, where
α>0, γ∈R and −π/2<θ<π/2. By convexity
arguments we prove that, under certain conditions on α,θ,γ,
a class of solutions with negative initial energy blows up in finite time