Creating lambda expression ConstantExpression with a string value

Question

I want to create lambda expression providing property name, a value (as string) and property type (as Type).

The problem with that is in line Expression.Constant(value1, propertyType);
value1 that is passed to Foo is string. and must be parsed to "unknown" type

static Expression<Func<T, bool>> LabmdaExpression<T>(string property1, string value1, 
                                                     Type propertyType)
{                              
    var parameterExpression = Expression.Parameter(typeof(TheObject), "o");
    var memberExpression1 = Expression.PropertyOrField(parameterExpression, property1);

    //casting?
    var valueExpression1 = Expression.Constant(value1, propertyType);

    var binaryExpression1 = Expression.GreaterThan(memberExpression1, valueExpression1);
    return Expression.Lambda<Func<T, bool>>(binaryExpression1, parameterExpression);
}