This is leaf scorch. In hot dry weather a tree can lose water from the leaves faster than it can be taken up through the roots, even if the soil is kept moist. This is worse if the tree is not drought hardy (red maple is not), and if it has an inadequate root system like your tree does because it is newly planted. All you can do is water it well and maybe mulch around it so it doesn't have to compete with the grass. I think that that is what you are seeing with the shrub too.