using System;

using Newtonsoft.Json;

public class Program

{

    public static void Main()

    {

        var blah = new { Date=DateTime.Now, Number=42 };

        var myClassWithAnonymousObject = new MyClass { MyString = "Hello", Something = blah };

        Console.WriteLine(JsonConvert.SerializeObject(myClassWithAnonymousObject));

        var myClassWithAnotherDatetime = new MyClass { MyString = "Hello", Something = DateTimeOffset.UtcNow };

        Console.WriteLine(JsonConvert.SerializeObject(myClassWithAnotherDatetime));

    }

    public class MyClass 

    {

        public string MyString { get; set; }

        public dynamic Something { get; set; }

    }

}