JsonDateSerialization

var settings = new JsonSerializerSettings
{
    NullValueHandling = NullValueHandling.Ignore,

    Converters = new List<JsonConverter> 
    { 
        new IsoDateTimeConverter()
        {
            DateTimeFormat= "yyyy-MM-dd HH:mm:ss"
        }
    }
};

var myContentJson = JsonConvert.SerializeObject(someObject, settings);